texts: Why does decreasing the pressure of the system increase the relative volatility of a binary solution?

texts:
In our teaching lab, we were posed with the following question as an exersize:

  If the boiling points of two compounds differ by $\pu{50 ^\circ C}$ at atmospheric pressure, what will be the effect on the relationship by decreasing the pressure to $\pu{1 mm}$ (no number, just a general process)?

I did not find much information on the subject in our lab manual or book but, but based off of some reading I've done around the internet (see below), it seems that for most binary solutions, decreasing the pressure increases the relative volatility.  However, asking some of my peers, they seems to believe that while both boiling points would decrease, the difference in their new boiling points would remain about the same (i.e. $\pu{\approx 50 ^\circ C}$), To make matters slightly more confusing, using a pressure-temperature nomograph, picking arbitrary numbers, I found that the relative volatility decreased (see Figure 1).

Who is more correct?  Does decreasing the system pressure increase the relative volatility or does it stay the same?
If the relative volatility increases when system pressure is decreased, why is this the case?  I would actually guess the opposite, because as you decrease the pressure towards $0$ (a vacuum), it would seem that all boiling points would approach $\pu{0 K}$, thus be getting closer together.
If the relative volatility increases when system pressure is decreased, does that mean it is always more efficient to perform fractional distillation under a partial vacuum?

Figure 1  Two nomographs measured via Pressure-Temperature Nomograph Interactive Tool by Sigma-Aldrich decreasing the system pressure to $\pu{1 mm}$ for two arbitrary substances with $\pu{50 ^\circ C}$ boiling point disparity at $\pu{1 atm}$.

References:

Effect of temperature or pressure on relative volatility chemengineering.wikispaces.com via the Internet Archive (under "Effect of temperature or pressure on relative volatility")
Industrial-scale applications of vacuum distillation at Wikipedia


texts: Destroying micellar particles using electrolytes

texts:
I learnt that micellar particles formed by ionic detergents forms due to the negative charges of H2O molecules are facing the solution, hence micellar particles repel each other.

I also learnt that micellar particles are destroyed upon the addition of an electrolyte, but I would like to know how.
My attempt: when aqueous cation and anion forms (from electrolyte), it means a lot of H2O molecules are 'consumed' to surround those ions. Therefore, fewer H2O molecules will surround the micellar particles, hence they will aggregate together (hydrophobic interaction?) and form suspensions.
I know my attempt has flaws e.g. when fewer H2O molecules surround the micellar particles, those Na+ are still present on the surface hence still repel each other, so I may be wrong.
I would like to know the real rationale behind it, thank you.


texts: Simultaneous Equilibrium Reactions, One Goes to Completion

texts:
Say I have the following reactions:

$\ce{CH4 + H2O <=> CO + 3H2}$

$\ce{C2H6 + 2H2O -> 2CO + 5H2}$

Which undergo these processes in the same container. The first reaction goes to equilibrium and the second to completion. Clearly the reactions are entangled as the products are the same. The equilibrium concentration of methane will intuitively depend on the initial amount of ethane introduced. I'm not sure how to go about calculating the equilibrium concentration of methane however. My first thought was to find the amount of carbon monoxide and hydrogen gas generated by the second reaction and use this as initial product in the first reaction and to calculate equilibrium concentration from there but I'm having trouble doing this.


texts:
We commonly use methane and propane for cooking (and home heating), but not ethane. I would expect ethane to be suitable for this, being in between the two, but I've never heard of anyone using it for this purpose. Why is that?

On a related note, why is butane used for cigarette lighters and basically nothing else (in ordinary life, I mean)?


texts: How do I reduce the smell of store-bought liquid soap?

texts:
I recently bought a brand of liquid soap I've never used before and it turns out they formulated it with a bit too much of the scent ingredients, to the point where I find it gets uncomfortably close to nauseating during use, and also it persists too long on my hands afterwards, compared to what I find normal.

How do I neutralize some of this scent, what can I try to mix in? All I can think of are baking soda or vinegar (but then vinegar also persists a lot and is unpleasant, plus it's acidic and I'm going to mix it with a probably-alkaline soap, and I don't want any crazy reactions and byproducts if possible).


texts: How is aqua regia stored as it dissolves all metals?


texts: Why does ozone, being heavier than air, not settle down?

texts: Is this because of some equilibrium between diffusion and gravity ? What exactly is responsible?


texts: Confusions regarding porous pot experiment

texts:
So, I have  studied  about  the porous pot experiment.Although I did understand the concepts of water level falling and rising due to difference in RMMs and thus difference in rate of  diffusion, I  still have two questions left:

Suppose hydrogen is outside the porous pot (in the jar), and carbon dioxide is in the porous pot...

Is the water level in the manometer in general dependent on just the gas in  the porous pot(CO2) or the whole mix of gas in the jar (H2 and CO2)?
Does all of the H2 diffuse into the porous pot or is  some of it left? I thought diffusion is  just the movement of gas particles to make the whole system balanced in concentration, so shouldn't there be an even concentration  of H2 in and out of porous pot?


texts: Does a geminal or vicinal diiodide form upon addition of excess HI to but-2-yne?

texts:
Reaction: $\ce{CH3-C#C-CH3 + HI (excess) -> ?}$
Product : I thought of different carbons by the reasoning from this post earlier I posted. But it is given that both iodine atoms exist on the same carbon.
Is this an exception or is the answer given incorrect?


texts: Does the 'X' of Grignard's reagent react?

texts: Till whatever I have studied in organic chemistry, Grignard's reagent has been the most helpful thing everywhere, whether is it preparation or reaction of organic compounds. But I haven't ever seen the Halogen part of RMgX reacting with any compound. Does the Halogen ever react in any reaction?


texts: Why does the Heisenberg uncertainty principle work in an atom?

texts:
Where is my logic wrong?

An electron can only assume quantized energies in an atom.

If an electron is localized in space in a hydrogen atom, its radius is known. If its radius is known, its electrostatic potential energy is known. Then, if the electron assumes quantized energies, its kinetic energies are quantized by $E_\mathrm{total} - E_\mathrm{potential}$ for all quantized possible total energies of the electron. This gives us quantized kinetic energy and thus momentum, giving us quantized frequencies. If you sum all of the waves of those frequencies, will it give the localized position wave-function? They can't right due to the fact that they're quantized.

This is probably very wrong; I just don't understand how.


texts: Is a C-D bond better than C-H bond?  I mean if carbon has a chance to either for a bond with deuterium or hydrogen what would it choose and why?  What if tritium competes too?


texts: Bromination of hexene in presence of UV light or heat

texts: The reaction between hexene and bromine in presence of light gives 3-bromocyclohexene. Why is 1,2-dibromocyclohexane not formed instead?


texts: How can I work out what reaction will happen?

texts:
I have recently started learning chemistry, and I've been reading a GCSE (UK high school level) textbook on the stuff :D

Much of it has been fairly straightforward, though there has been a reoccurring theme that has been bothering me.

I've encountered many instances where the author simply presents a reaction with little explanation, as if to suggest that the reason as to why it would occur is obvious.

Let me give you an example I have come across just today. Ethene in bromine water:

I think to myself, 'why would this happen?'. There are no 'free electrons' that I can see in ethene. OK, bromine is highly reactive, but what will it do? Will it react with H, or C, and how? What about the bromine bond? It's all very uncertain in my mind.

I always try to reduce it to an energy problem. We just want the most stable state, right? But, there are many possible outcomes. Am I supposed to apply some logic, follow some flowchart, or work out all possible outcomes and calculate which has the lowest energy? Do chemists just remember all simple reactions, and reduce problems to those? Or, am I just overthinking it?

A side problem to this is why, if we place an alkane in bromine water, we don't get the same thing happening with ethane.


texts: Why is the molecular structure of water bent?

texts:
Water has the formula $\ce{H2O}$ and we can draw a Lewis structure with two lone pairs on the central oxygen. As a physics student and not a chemist, I think to myself, "Okay, there are two lone pairs, they will repel each other" and so we arrive at the conclusion of bent shape.

The issue in my mind is that I don't see why the lone electron pairs have to exist on the same side of the atom. Also, wouldn't the Schrödinger equation provide an equally plausible structure for water with the lone pairs on the opposite side of the oxygen from what we assume (imaging the electrons on the top or on the bottom of the oxygen in the Lewis structure)? If that were true, then there would be a resonance structure between the two states and we would get a linear geometry. Clearly I'm running around in circles here, please someone enlighten me!


texts:
Normally, I think about orbitals interacting in the context of bonding. When two atomic orbitals overlap, they can do so in-phase or out-of-phase. The in-phase overlap results in a bonding molecular orbital with lower energy than the original AOs; conversely, the out-of-phase overlap results in an antibonding MO with higher energy. Valence electrons fill the bonding MOs first, resulting in a bond.
The explanation of steric effects that I often hear is that they are caused by the overlap of two electron clouds, resulting in repulsion. Since electron clouds are just composed of occupied orbitals, how is this "overlap of electron clouds" different from the picture of bonding I described above? Does the steric repulsion just come from occupied antibonding MOs? I imagine that inner shell electrons and Coulomb forces must play a role as well, right?
@matt_black answered a related question about steric vs eletronic effects by saying:

The normal distinction between "steric" and "electronic" is based on whether the effect is transmitted through space or through bonds

I guess I'm essentially asking a follow-up question on how effects are transmitted through space.


texts: Soaps come in different colors, but why is soap lather always white?

texts: Soap comes in different colors, but why is soap lather always white?


texts: Why does free-radical chlorination of isopropyl bromide give 1-bromo-2-chloropropane?

texts:
Source: Morrison and Boyd - Chapter Alkanes - exercise no. 15

  Free-radical chlorination of either n-propyl or isopropyl bromide gives 1-bromo-2-chloropropane, and free-radical chlorination of either isobutyl or tert-butyl bromide gives 1-bromo-2-chloro-2-methylpropane. What appears to be happening? Is there any pattern?

I have really no idea how this can be happening.


texts: When $\ce{CO2}$ reacts with water, it supposedly forms $\ce{H2CO3}$, which is the aqueous form of $\ce{CO2}$. But it is hard to isolate, but its $K_\mathrm{a}$ value is pretty low (on the order of $10^{-7}$) indicating it should be found in a non dissociated form? So does $\ce{H2CO3}$ exist in solution?


texts:
Are acyl chlorides such as $\ce{CH3COCl}$
 acidic in water or any other solvent?

Are they in any context referred to as acid chlorides? Or is that just a mistake?


texts: What happens to the Lithium halide salt when reacting Lithium metal with alkyl halides?

texts:
In organic chemistry, I learned a lot of useful reactions but unfortunately I didn't get to try many of them first hand (what's sad is I am a Chemistry major too).  I've searched the internet back and forth for the answer to this question which I am fairly sure I know the answer to, but I thought I would just double check.

When reacting lithium with an alkyl halide (the reaction requires 2 mol Li metal per 1 mol of the alkyl halide), one mol of lithium forms the organometallic compound while the other forms the lithium halide salt.  The reaction takes place in diethyl ether, so my question is does the halide salt fall out of solution or not?  I would assume so considering diethyl ethers low dielectric constant in combination with the ionic character of Lithium salts, but I thought I would ask in hopes someone on here has performed this reaction first hand.  Thanks!

Edit: So I read LiCl has minimal solubility in diethyl ether, but LiBr is moderately to highly soluble which makes absolutely no sense to me.  I guess perhaps the lone pairs on oxygen might play a role in this but then again why wouldn't this have the same affect on LiCl?


texts: What is the mechanism of reaction between alcohol and PCl5

texts: Is this one correct? If not why and what is the correct one?


texts: What is the oxidation state of iron in $\ce{CuFeS2}$? And also could you please tell it's proper representation: $\ce{Cu2S.FeS.FeS2}$ or $\ce{Cu(I)FeS2}$?


texts:
In my introductory chemistry course, we learned that for reversible processes, entropy is defined as $ΔS = q/T$. However, we did not spend that long on this before moving on to other things like Gibbs free energy. My questions are:
1. What exactly is a reversible process?
2. Why must we use things like standard molar entropies to calculate $\Delta S$ instead of just using $\Delta H$ according to this equation?


texts:
What is a non-classical carbocation?
How is it different from a classical carbocation?

I am confused as I have come across this term many times on Chem.SE but there seems to be nothing for my level of understanding on the Internet!


texts: electronegativity and how it relates to bond strength

texts:
my question is, if the strength of the bond between two atoms increases as the difference in electronegativity increases as well.

so say, a H-F bond would be stronger than a O-H bond.

I'm a little confused because I know that acidity increases from left to right across the periodic table. So H-F is a stronger acid than H-CH3. Wouldn't this mean that H-F has weaker bonds than H-CH3?


texts: Can salicylic acid be synthesized from salicylaldehyde?

texts:
You have a bottle of salicylaldehyde. And you want to make salicylic acid from salicylaldehyde. You can use all reagents and catalyst to make salicylic acid.

I think salicylic acid can be synthesized from salicylaldehyde since salicylaldehyde has a structure similar to salicylic acid. I'm thinking that it might be possible to use $\ce{KMnO4}$, but I'm afraid the hydroxyl group attached to the benzene would be oxidized too.


texts: Radial Distribution Function for a Hard Sphere Gas in the Percus-Yevick Approximation - Is There a Quick Way to Evaluate it Numerically?

texts:
The question is as in the title.

I know that for a one-component hard-sphere gas, there is an analytic solution in the $\vec{k}$-space (PRA, 5, 939). I know that to obtain the correct solution in $r$-space I just need to do something like a Fast Fourier Transform. The problem is that in doing so I can only obtain values for the radial function on a grid, and problem arises as to the magnitude of errors on the grid values, the errors in interpolating between the grid values, and so on.

I have to apologize for the fact that I rarely do fast fourier transforms, and even less estimate their errors.

Is there a standard way (e.g fitting formula) to do this? Thanks.


texts: Why is the initial carbocation not formed adjacent to the phenyl moiety?

texts: I know that after rearrangement the carbocation is more stable, but we should protonate the compound first where the carbocation it is more stable, i.e.  adjacent to the phenyl group. Why do they suggest a different pathway? Is the shown correct?


texts: Spectroscopy: What is an instrument response function?

texts: Many papers involving ultrafast spectroscopy measure the instrument response function and model it as a Gaussian, but the sources on any of this are never cited and I have no intuition for what this could mean. What is the instrument response function intuitively and why is it represented as a convolution?


texts: Why do chloride ions not bond to water molecules/hydronium ions when hydrochloric acid dissociates?

texts:
I am a high school student and I was reading a textbook and it gave me the equation of this hydrochloric acid which was put into water and the products formed were hydronium and chlorine.

$\ce{HCl + H2O -> H3O+ + Cl-}$

I understand that $\ce{HCl}$ (Hydrochloric acid) breaks up in the water to become 2 free ions (Hydrogen & Chlorine) and the Hydrogen bonds to the water because of electronegativity that causes the oxygen to be partially charged and so the $\ce{H+}$ will bond to water giving us $\ce{H3O+}$. This makes sense to me however I do not quite understand why $\ce{Cl-}$ is left "alone".

If there is a lot of water with only little amount of acid added surely it should lead to the $\ce{Cl-}$ also bonding to water or hydronium? Why does it not bond to them?

My Hypothesis

I have attempted to use my knowledge of physics and chemistry to tackle this problem, I am not as well-versed in chemistry so please bare with my "beginners" attempt at understanding this.

Water ($\ce{H2O}$) is a polar molecule due to electronegativity so perhaps as the chlorine is trying to attach to the hydrogen part of the molecule the oxygen's negative field is slightly stronger than the attractive forces of the hydrogen in the molecule of water thus the chlorine cannot bond with the water.

Next hydrogen is covalently bonded to water so their outer orbitals are filled up so there is no need for the chlorine to even bond as the hydrogen has filled its orbitals.

Please criticize my thinking as it will only improve my scientific curiosity and intuition.


texts: Comparing radii in lithium, beryllium, magnesium, aluminium and sodium ions

texts: Apparently the of last four, $\ce{Mg^2+}$ is closest in radius to $\ce{Li+}$. Is this true, and if so, why would a whole larger shell ($\ce{Mg^2+}$) be closer in radius to $\ce{Li+}$ than its isoelectronic neighbor ($\ce{Be^2+}$) with just one extra proton?


texts: From EN alone we might expect $\ce{HCl}$ to be more polar but a book says that the bent structure of $\ce{H2S}$ gives rise to its polarity - which is also apparently more than $\ce{HCl}$. Why? Does this have to do with the lone pairs? Lone pairs supply electron density, right?


texts: What is the preferred IUPAC name of o-toluidine?

texts:
Why does o-toluidine have 2-aminomethylbenzene as its IUPAC name?

Why isn't it named as a derivative of amine (like 2-methylaniline)? Aren't amines given a higher priority than alkanes in nomenclature?

See the Priority Chart given on Master Organic Chemistry for reference.


texts: What is the correct way to pronounce iodine?

texts: I have always said it like 'io-deen' because whenever 'ine' is used (eg. amine, or fluorine) it is said that way. Sometimes I'm corrected by people who think it should be pronounced 'io-dyne', which is correct?


texts: How do non-ionic compounds dissolve into water? Into molecules or atoms?

texts:
I can't seem to find the answer in google, which is surprising.

I'm aware that ionic compounds dissolve into electrolytes. However, when non-ionic sacarose for example dissolves in water, does the sacarose crystals break into single atoms as well or does it stay as a whole molecule in water? What does exactly happen?

Thanks everyone =)


texts: Number of spatial arrangements of tetrasubstituted biphenyl

texts:
According to my book 2-bromo-2'-(1-chloroethyl)-6'-iodo-6-(prop-1-en-1-yl)-1,1'-biphenyl has eight possible spatial arrangements. How can this be so? I can think of only four – left two groups being planar with right two groups up-down and down-up, and vice versa.
For this configuration of I and $\ce{CHClCH3}$ I can think of four, for I and $\ce{CHClCH3}$ interchanged I can think of four more, but that is not the same molecule and is just a configurational isomer.


texts: In such reactions as in the pic, how can we know which carbonyl group will undergo a reaction to give an alcohol. Also, can both of the sites undergo the reaction?


texts: Major product in reaction of butan-2-one + selenium dioxide

texts:
When reading about $\ce{SeO_2}$ I read this following reaction:
$\ce{CH3CH2COCH3 ->[SeO2] CH3CH2COCHO + CH3COCOCH3}$
In the following reaction it was stated that $\ce{CH3CH2COCHO}$ was the major product. But I fail to understand why ?
The two possible reasonings I can think of are that the terminal hydrogen is either less sterically hindered or that it is more acidic. But I am not quite sure of either.
What is the reason for the same ?


texts: Geometry of a free radical at the bridgehead carbon

texts:
With reference to J. Am. Chem. Soc. 1968, 90 (19), 5266–5267, they state:

The most favorable geometry of aliphatic free radicals remains an unsolved problem, since existing data are consistent with a geometry which is either pyramidal and rapidly inverting, or planar but easily deformed.2-4 One approach to the problem is generation of the radical
at a bridgehead of a bridged bicyclic system. [...] From their aldehyde decarbonylation study, however, Applequist and Kaplan concluded that 1 -adamantyl and 1 -bicyclo[2.2.2]octyl were appreciably more stable than t-butyl. 3
3. J. Am. Chem. Soc. 1965, 87 (10), 2194–2200

which is later concluded as:

[...] The extent of geometrical destabilization is considerable, and we conclude that alkyl radicals tend toward planar geometry. The lesser extent of destabilization, relative to that for the carbonium ions, might mean that radicals seek a flattened pyramidal state. [...] This issue can evidently not be settled without spectroscopic information about alkyl radicals.

Has there been any further studies on the geometry of free radicals at the bridgehead carbon?


texts: How does Fe2+ become Fe in sacrificial protection?

texts:
I've searched low and high on the internet, but nothing to help me.

I know that zinc is oxidised in preference to iron, and that it "donates" those two electrons to iron.
$$\ce{Zn -> Zn^2+ + 2e-}$$

But how does iron make use of those two electrons to revert back to iron when it turns into iron oxide, like so:

$$\ce{Fe^2+ + 2e- -> Fe}$$

Doesn't the $\ce{Fe^2+}$ in the $\ce{Fe2O3}$ need to be dissolved in water? How can it be affected by $\ce{2e-}$ travelling along? Maybe I am missing something.


texts:
Why do Hydrogen Halides(with the exception of HF) form mostly strong acids?
My guess is that the negatively charged Halide part of the molecule is attracted by the partially positive part of the water molecule. Thus it is separated more easily. Although because it has one more electron it is more stable once it has dissociated


texts:
I am supposed to predict the product of rearrangement of this cation, having been told that it's an oxyallyl cation:

I did have a look at the Wikipedia entry (since it mentions "oxyallyl cation") and not even once does it mention such a compound as I have shown above. This question is from my high school text book chapter on "Aldehydes and Ketones", and I'm not sure I'm even supposed to know what to do here in the first place.

Anyways, I did guess that the negatively charged oxygen atom will donate its lone pair to the positively charged carbon atom1, forming a three member hetero-ring. But, my book gives the correct answer as:

I'm not sure where they dumped the second oxygen atom (and from where they brought an extra carbon atom) to form this all-carbon ring. Also, is that $\ce{-OMe}$ at the ortho position only for ornamental purposes, or does it affect the mechanism in some way?

Source: MS Chouhan; Advanced Problems In Organic Chemistry; 11th ed; page 218 in solution manual, Q91 chapter on Aldehydes and Ketones

1: Yeah I know that all these atoms are in conjugation and the charges are only partially negative/positive.


texts:
The order of nucleophilicity for halide family in DMF is:  $\ce{Cl- > Br- > I-}$. I understand the reason for this must be that DMF, being a polar aprotic solvent, is unable to solvate the halide ions.

I was told by my teacher that this is true only for DMF and DMSO, while in other aprotic polar solvents, the order is as usual: $\ce{F- < Cl- < Br- < I-}$.

I'd like to know what is special about DMF and DMSO (and which is not possessed by other aprotic solvents like acetone) that leads to this order.

I have verified the order in DMF from March's 7th edition (page 427). The book mentions the usual order ($\ce{Cl- < Br- < I-}$) for acetone (another aprotic polar solvent).


texts: How to know it when I see a covalent network?

texts:
This is a well-known (better said: well-discussed) question in the internet. When you look for answers for popular questions, you usually see them with a variable degree of reliability and complexity. Unfortunately, for this one, I only observed very very crude and general rules of thumb. So let's get a real answer:

  A network solid or covalent network solid is a chemical compound (or element) in which the atoms are bonded by covalent bonds in a continuous network extending throughout the material. In a network solid there are no individual molecules, and the entire crystal may be considered a macromolecule. Formulas for network solids, like those for ionic compounds, are simple ratios of the component atoms represented by a formula unit. Covalent network, wikipedia

Diamond and SiO$_2$ are really great examples of covalent networks-lattices. So enough with stories:

If you face a new chemical formula, how would you assume it's a covalent network? (In case it is) Is it somehow done by drawing the Lewis structure? Is there a rule for this? Or is it only possible to know such thing with experimental data?

Fun fact: I'm preparing for an internal chemistry olympiad. The examiners usually take all the exceptions into account. So general rules such as "if it contains Si, it's a covalent network" aren't really reliable for me. Better phrased, I'm looking for a rule with the least exceptions.


texts: Is sodium hypochlorite solution an ionic solution - does it conduct current?

texts: Does an aqueous solution of sodium hypochlorite conduct current?


texts: Could we reach a pH of 4.9 by blowing through straws?

texts:
According to Wikipedia's article on Breathing:

  The permanent gases in gas we exhale are 4% to 5% by volume more carbon dioxide and 4% to 5% by volume less oxygen than was inhaled.

If I started with a clean beaker of pure water and measured the pH carefully and quickly, I might get a value close to 7.0. If I left it out in the air for a while, far from concentrated sources of pollution, it would equilibrate with the local CO2 concentration which would be 300 to 500 ppm depending on local variables and natural sources (people, plants), and that would lead to a (carefully) measured pH below 6, and probably somewhere around 5.8 or 5.7. Is that about right so far?

Now suppose that I then took turns with lab mates and constantly blew bubbles into the water through long straws that contained some charcoal and other filters to absorb organics from my breath, leaving only the added 4 to 5% CO2 from our respiration.

If the average area of all the bubbles present was about the same or greater than the average area of the water exposed to the air, would I be roughly correct in using a number like 0.02 or 0.03 atmospheres for the CO2 partial pressure in the plot as displayed below, and getting a pH of about 4.9?

Is this what would happen, or are there significant effects that I've neglected?

related: answer to Formation of carbonic acid from breath?

Screenshots from Effect of Dissolved CO2 on the pH of Water, Byck, Harold T., Science  19 Feb 1932, Vol. 75, Issue 1938, pp. 224, DOI: 10.1126/science.75.1938.224.


texts: How to calculate the concentrations of conjugate species present in the solution of diprotic acid?

texts:
Calculate the concentration of $[\ce{SO_3^-^2}]$ present in 0.010M solution of $\ce{H_2SO_3}$ in pure water?

($Ka_1=0.017)$, ($Ka_2=10^{-7.19}$)

I found this approach in reference text for solving the problem :

But I confused with the derivation of Eq.2, so I do my calculation according to Eq.1 to find the concentration of sulfite ion equal
$2.20×10^{-7}$ M.

SO :

I choose another approach to find the concentration of sulfite ion depending on substitution in this formula :
$$Ka_2 = \dfrac{\ce{[H+][SO3^{2-}]}}{\ce{[HSO3^-]}}\ $$
Thus

$$\mathrm{10^{-7.19}} = \frac{(0.00706 + {[SO_3^{-2}]}){[SO_3^{-2}]}}{(0.00706 - {[SO_3^{-2}]})}$$

From which I obtain
$$[\ce{SO_3^{-2}}] = 6.46 \times 10^{-8}$$
Which different from the answer obtained from the first approach.

I appreciate any help.


texts: Definition of the B3LYP functional in common QC programs

texts:
I wanted to use custom functionals with Gaussian and came up with some interesting definitions of the B3LYP functional within Gaussian, Orca and Turbomole, ...

$$\small\begin{array}{lcccccc}
\hline
  &  \text{Gaussian}  &  \text{ORCA}  & \text{Turbomole}  &  \text{NWChem} & \text{Molpro} & \text{GAMESS(US)}\\
\hline
\text{HF}  &  0.2  &  0.2  &  0.2  &  0.2  &  0.2  &  0.2\\
\text{Slater}  &  0.8  &  0.8  &  0.8  &  0.8  &  \color{red}{0.08}  &  0.8\\
\text{Becke}  &  0.72  &  0.72  &    0.72  &  0.72  &  0.72  &  0.72\\
\text{VWN-x}  &  {\color{red}1}  &  {\color{red}{1}}  &  0.19  &  0.19  &  0.19  &  0.19\\
\text{LYP}  &  0.81  &  0.81  &   0.81  &  0.81  &  0.81  &  0.81\\
\hline
\end{array}$$

It seems to be clear, that all programs define it somehow similar, but there are also some points that made me curious about the definitions. Let's start with the overall structure of this functional:

$$\text{XC-Functional}=a E_x^\text{local}+(1-a)E_x^\text{HF}+b E_x^\text{non-local}+c E_c^\text{non-local}+(1-c) E_c^\text{local}$$

The Gaussian documentation for DFT inputs specifies how one could change the amounts of each "sub-functional" by using the IOp-Statements through:

IOp(3/76=mmmmmnnnnn) IOp(3/77=mmmmmnnnnn) IOp(3/78=mmmmmnnnnn)

Where mmmmm and nnnnn will get divided by 10000 and 3/76=$P_1P_2$, 3/77=$P_3P_4$ and 3/88=$P_5P_6$. Those $P_{1,..,6}$ values are part of the following equation, which is a modified version of the equation above.

$$\text{XC-Functional}=P_2 E_X^\text{HF} + P_1 \left(P_4 E_X^\text{Slater} + P_3\Delta E_x^\text{non-local}\right) + P_6 E_C^\text{local} + P_5 \Delta E_C^\text{non-local}$$

Combining both, this yields: $P_1 = \{1,0\}$, $P_2 = 1-a$, $P_3 = b$, $P_4 = a$, $P_5 = c$ and $P_6 = 1-c$.

Now looking at Gaussian and ORCA, they both use 100% VWN and 81% of LYP, which should actually be combined to give 100% (instead of 181%) as is done by all other mentioned programs through using 19% VWN and 81% LYP.

It seems, that I am lacking some important information to understand that definitions in both, Gaussian and ORCA, and I hope seriously, that someone can enlighten me.

PS My discussion with Martin came up with the possibility, namely that there might be some missing brackets in the second equation, giving the following:

$$\text{XC-Functional}=P_2 E_X^\text{HF} + P_1 \left(P_4 E_X^\text{Slater} + P_3\Delta E_x^\text{non-local}\right) + P_6 \mathbf{{\color{red}(}}(1-P_5)E_C^\text{local} + P_5 \Delta E_C^\text{non-local}\mathbf{{\color{red})}}$$

Appendix: Information from the program output or the documentary

Gaussian 09 Rev. A.02 output

IExCor=  402 DFT=T Ex=B+HF Corr=LYP ExCW=0 ScaHFX=  0.200000
ScaDFX=  0.800000  0.720000  1.000000  0.810000

ORCA 3.0.3 output

Fraction HF Exchange ScalHFX         ....  0.200000
Scaling of DF-GGA-X  ScalDFX         ....  0.720000
Scaling of DF-GGA-C  ScalDFC         ....  0.810000
Scaling of DF-LDA-C  ScalLDAC        ....  1.000000
Perturbative correction              ....  0.000000
NL short-range parameter             ....  4.800000

Turbomole 7 define

 b3-lyp          | HYB  | 0.8S+0.72B88   | 0.19VWN(V)     | 1-3,5,6,10
                 |      | +0.2HF         | +0.81LYP       |
 b3-lyp_Gaussian | HYB  | 0.8S+0.72B88   | 0.19VWN(III)   | 1-3,5,6,10
                 |      | +0.2HF         | +0.81LYP       |

NWChem
Molpro

B3LYP   EXACT:B88:DIRAC:LYP:VWN5    0.2:0.72:0.08:0.81:0.19

the 0.08 is probably a typo
GAMESS(US)


texts: Calculating volume % in a mixture of gases at equilibrium

texts:
In a mixture of $\ce{N2}$ and $\ce{H2}$ initially In a mole ratio of $1:3$ at $\ce{30 atm}$ and $\pu{300^\circ C}$, the percentage of ammonia by volume under the equilibrium is $17.8$. I have to calculate the equilibrium constant $K_\mathrm p$ of the mixture for the reaction
  $$\ce{N2(g) + 3H2(g)<=>2NH3(g)}$$

When I read the question, the first thing that comes to me is Dalton's law of partial pressure and (I think) that according to that law we can imagine the components of gaseous mixture occupying a volume ($V$) each equal to the total volume of container. Thus, that is why we simply write the partial pressure of any gas as ($P_iV=n_iRT$) and sum all the partial pressure to get total pressure.

Coming back to original question, according to the previous logic, each gas in the container at equilibrium is occupying same volume ($V$) equal to the total volume of the container. Then the term volume % doesn't make any sense because each gas is occupying the whole volume of the container (under ideal gas assumptions) so volume% of each gas $= 100\%$.

So what does the question mean by "Volume %" (for gases)? Is there any flaw in the above logic?

P.S: I would have easily solved the question if mole % was given as each gas has different moles so no problem there.


texts: Why does boron fume in moist air? Is the following accurate?

texts:
I initially guessed it was due to the formation of $\ce{H3BO3}$ but am now doubtful. Does it have anything to do with $\ce{HCl}$ formation? If the question referred to a boron halide, I could answer with that. Either the question is wrong, or my guess is. What's accurate?

I'd appreciate any help.
Grade 11 Chem.


texts: Is the Arrhenius Equation only valid for reactants in the gas state?

texts:
I couldn't find a source that explicitly say this, but given the gas constant R is used, is the Arrhenius equation only valid when all reactants are gases? Do they have to be ideal gases?

If the above is true, is there a similar equation for reactions where at least one reactant is in liquid/solid form?


texts: Is there a name for the pair (c, R), where c is the stoichiometric coefficient of a reactant R in some chemical reaction?

texts: I am programming a simulation, and I need a good name for a data structure that stores pairs $(c, R)$, where $c$ is the stoichiometric coefficient of a reactant $R$ in some chemical reaction. Is there a name for these pairs $(c, R)$ in chemistry?


texts: Why is carbon monoxide a monodentate ligand

texts:
Carbon monoxide has lone pairs on both the carbon and the oxygen atoms. However, I have never seen any complex where the oxygen atom or both the oxygen and the carbon atoms are the donors.

I know that the much lower electronegativity of carbon makes it a much stronger donor. However, this difference in electronegativity exists in the cyanide ion too, albeit a little less. However, cyanide ion is ambidentate.

My question basically is :
Why is carbon monoxide not an ambidentate ligand? Further, why is it not bidentate?


texts: What is the term for a compound where one element exists in two oxidation states in the same molecule?

texts: Example nitrogen in $\ce{N2O}$ (−3 and +5). I'm pretty sure there's a term but I've forgotten what it is I thought it was disproportionation but this seems to only refer to a reaction


texts: How accurate is this polar mechanism for the Diels-Alder reaction?

texts:
So the prof got to Diels-Alder without discussing it in the context of molecular orbital theory. Instead we got a resonance picture of what happens... this is what he told us:

1) 1,3-butadiene has both an electrophilic and a nucleophilic terminal carbon atom because we can draw resonance structures showing dipolar terminal carbon atoms ...

2) For ethene we can similarly draw a dipolar resonance structure.

From there we're told to simply use Coulomb's law - opposite charges attract - to complete the mechanism.

So, how adequate is his electrostatic explanation? Is it adequate - probably ... if one simply wants to learn it for a test. But is it conductive to further understanding of chemistry? I feel rather short-changed here since I'm paying him the big-bucks (tuition is insane) and the book goes into far greater detail ...

ETA: I asked the guy about and grilled him on the electrostatic explanation. For example I raised Martin's excellent point about the fact that the dieneophile cannot be that polarized - otherwise wouldn't it be a liquid instead of a gas due to the strong intermolecular attractions?

He instead went on a tangent on electron-withdrawing groups and how the electrostatic explanation can explain these ... what do you think?


texts: Organic chemistry textbook for self-learning?

texts:
I am interested in learning organic chemistry in order to solidify my knowledge of molecular biology.

However, there are a lot of options for organic chemistry textbooks, and I plan on simply sampling a few in order to figure out which ones are best, but I thought I would also ask for some advice.

Since I am self-learning, I have some specific items on my textbook wishlist:

The textbook should be insightful - I don't simply want facts presented, I want to see how the facts connect together into a larger whole. Usually, teachers fulfill this task, but in this case, I will need some help from the textbook.
The textbook should have a good section on learning IUPAC nomenclature.
I don't want organic chemistry to be an experience in advanced memorization for me. The previous point helps in addressing this issue, but I would like to reiterate it. I would like to have a textbook that helps me understand why each class of reactions is important (what can one do, that the other can't?) in a chemist (or an organism's) toolbox - I don't want to be memorizing reactions, I want to be putting them into my toolbox.

With such requirements in mind, which textbooks would you recommend?


texts: Why are the masses of atoms less than the sum of their subatomic particles?

texts:
The mass of carbon-12 is $\pu{12 u}$ by definition. However, one carbon-12 atom comprises 6 neutrons (each weighing $\pu{1.0087 u}$), 6 protons (each weighing $\pu{1.0072 u}$), and 6 electrons (each weighing $\pu{0.0005 u}$), which all add up to $\pu{12.0894 u}$.

Where does the $0.7\%$ difference in mass come from?


texts: Electronic States of the (unstable) tetrahedral CrCl4

texts:
I was probing for first order Jahn-Teller instability in the coordination complex CrCl4 (2 electrons in E set). Taking the direct product yields the states A1 + A2 + E, so I took the symmetric and antisymmetric direct products too to see which states represented a singlet and triplet configurations.

To my surprise, the symmetric direct product yields 2A1 + E while the antisymmetric product yields A2 -A1. I believe that I probably made a mistake somewhere (but can’t find it), so did I make a mistake somewhere in my working, or is there an actual meaning behind a negative irreducible representation?

Thanks!


texts: Is it appropriate to approximate solute particles in a dilute solution as an ideal gas?

texts:
I was studying osmosis and I came across the formula for osmotic pressure. I decided to see the derivation for osmotic pressure in a dilute solution. The derivation involved an equation involving the chemical potential, fugacity and so on, which I am not familiar with. I have been introduced to very little thermodynamics. So I decided to come up with my own justification regarding the osmotic pressure formula. I want to know is there any thing wrong in my explanation.

Suppose we take a u-tube containing pure water. The level of water in both arms of the u-tube will be the same and hence also the pressure in both of the limbs. Now suppose I take a u-tube containing pure water and a dilute aqueous solution separated by a semi permeable membrane. The pure water from one limb will flow towards the other limb through the semi permeable membrane until equilibrium. In equilibrium the side of the u-tube containing the dilute solution will have a higher pressure (as seen due to greater rise in height). This extra pressure is due to the dissolved solute particles (if solute particles were not there both arms of the u-tube would have the same pressure). This extra pressure due to the solute particles is the osmotic pressure. Since the solution is very dilute, the solute-solute interactions can be neglected and we consider the solute particles as an ideal gas occupying the volume of the solution. Thus to find the pressure exerted by the solute particles we can use the ideal gas law. Hence this pressure is the osmotic pressure.


texts: Avogadro Molecule Editor: How to render image from command line?

texts:
Given a molecular geometry in the .xyz file format, how can I use Avogadro on the command line to render an image of it?

The website states that there is some command line API available, but I can't seem to find any documentation/information about it. Alternatively, are there any other molecular visualization tools that provide a convenient command line interface for image rendering of .xyz files?


texts: Why can zwitterions be difficult detect by HPLC-MS?

texts:
I understand that to separate molecules by HPLC (or SFC) you commonly adjust the pH of the mobile phase to get preferable charges (i.e. negative charges) on the molecules - so that they interact with the column and are therefore well separated and thus give a large distinct peak.

Im not completely sure I understand what happens to zwitterions like amino acids when you try to separate them. Is it correct to think that they randomly interact with the column and thus "spread out"resulting in a chromatogram with a lot of noise? Why is it that the connected MS also has problems detecting them (should it not continuously detect the molecule)?

Example of amino acids that could be difficult to detect:


texts: Why does aqueous NaCl conduct electricity?

texts: Could someone please explain why an aqueous solution of NaCl conducts electricity? I've Googled this up but couldn't get a satisfactory answer. This has an answer on Physics.SE but that's too complicated. My textbook doesn't answer my question.


texts: Why do these two IUPAC naming examples not begin numbering the chain closest to the alkyne?

texts: I am currently reading my chemistry book which states "The chain is numbered from the end closest to the triple bond." However, then it proceeds to give two examples which I do not believe follow this rule. What is the reasoning for this?


texts: Are there any reactions where two triatomics form three of the same diatomic?

texts:
A chemical equation: $\ce{A}+\ce{B}\to\ce{3C}$

Where $\ce{A}$ & $\ce{B}$ are triatomic molecules and C is a diatomic molecule. Find out $\ce{A}$, $\ce{B}$, $\ce{C}$?

So far the most worthy options for answer I've found are  $\ce{S_3}$ (trisulfur) and ozone ($\ce{O_3}$) as $\ce{A}$ & $\ce{B}$ and $\ce{SO}$ as $\ce{C}$. But I am not sure if this reaction will occur : $\ce{S3 + O3 \to 3SO}$

So, are there any better options? I am even worried about if this even has an answer in chemistry known to this day.


texts:
Why has lithium bromide a slight solubility in organic solvents?

Theoretical, LiBr is an ionic compounds, so it should be only soluble in polar solvent like water. But why is it soluble in others?


texts: Fragmentations and rearrangements in n-(4-alkyl phenyl) alkanoic acids in mass spectrometry

texts:
I have this example exam question for which I don't have the answer. I have been working on it the whole morning but I can't figure it out. The question suggests three molecules, only one of which corresponds to a given fragmentation table and mass spectrum following EI-based MS.

The molecules are 4-(p-hexyl phenyl) butyric acid:

and two variants where the phenyl is shifted one to the left (pentylphenyl pentanoic acid) or one to the right (heptylphenyl propanoic acid).

The table and EI-MS spectrum are unfortunately not of ideal quality, but they are as follows:

The 177 and 188 were given to both be directly stemming from the molecular ion, and with one of them having an even and the other an odd mass, this suggests a simple cleavage and a cleavage following rearrangement.

With pentylphenyl pentanoic acid I got close, but the fragment following rearrangement is 192 Da instead of the 188 Da seen in the spectrum.

UPDATE - Let me add two other examples of what I have tried so far. Maybe there is something wrong with my approach or someone can see the obvious change that would get to an observed peak at 188 m/z from here. The fragmentation on the left (below), is where there actually are 188 and 60 fragments, but the 60 fragment carries the charge (this peak at 60 m/z can be seen in the spectrum). On the right, I tried to get to a similar fragmentation while starting by putting the charge on the phenyl.


texts: Is the rate of electrolysis the same throughout as long as voltage is same

texts:
In an electrolytic cell, where the electrolysis of dilute sulfuric acid is taking place, would the rate of electrolysis be constant always, even at the beginning?

By rate of electrolysis, I mean the rate of gas production or the rate of charge delivery. And would this rate be established as soon as I turn on the voltage, or does it slowly increase to a constant level?


texts: Physical significance of double-well potential in quantum bonding

texts:
I'm currently studying about the hydrogen bond's Potential Energy Surface (PES) pattern.
As per literature, single point energy obtained from Density Functional Theory (DFT) using MP2 approximation performed with Gaussian software (www.gaussian.com) showed the pattern of Lennard Jones Potential (LJ-potential). A Lennard Jones is a one-well potential http://www.cmbi.ru.nl/redock/:

However, in certain literature it is also shown to obey the double welled potential model (PES_vs._atomic-distance response).

Having said that, I'm basically wondering about the physical significance of a double-well potential model with respect to interacting-atoms, in case of hydrogen bonds. Any insight or reference towards deciphering the concerned fact would be highly appreciated.


texts: Total irreducible representation of a quantum system - Slater determinant?

texts:
I'm beginning to study quantum chemistry and I became pretty confused about the total state of the molecule.

When we describe the single orbitals using irreducible representations like in the picture below, then we can get the total quantum state by direct product
$$(2a_1)^2(1b_2)^2(3a_1)^2(1b_1)^2=(A_1)^2\otimes (B_2)^2\otimes (A_1)^2\otimes (B_1)^2 =A_1,$$

as it is described in this answer. But when I read about multi-particle wavefunctions, I realized, that the wavefunction of the whole system should be antisymmetric, so I should assemble Slater determinant to get the multi-particle wavefunction with the enforced antisymmetry property.

Questions

1) How is Slater determinant connected with the direct product above?

2) Does $(A_1)^2$ mean $A_1 \otimes A_1$ or is it purely the notation for 2 electrons in the orbital?


texts:
Isocyanides are the only class of organic compounds which possess a divalent carbon. They react like a geminal nucleophilic/electrophilic synthon with oxidation of the C(II) atom to C(IV), which parallels the chemistry of carbenes and carbon monoxide.

Some of the most common methods for synthesizing isocyanides involve the dehydration of formamides. Various dehydrating agents (phosgene, phosphorus oxychloride) are used in the presence of a base (pyridine/TEA). In the follow reaction, however:

$\hspace{2.4cm}$

I'm unable to understand the role of p-TsCl, and can't work out the reaction mechanism.


texts: Why do we still need to know about the Rankine temperature scale?

texts: I am learning process principles in chemical engineering and I was taught various temperature units like Fahrenheit, Celsius, Kelvin, and Rankine. I see the first three being used quite commonly, but I rarely see the fourth being used. Where is the Rankine scale used then?


texts: How do I know how many molecules a solute will split into when it dissolves in a solvent?

texts:
I'm in high school and I'm learning about freezing point depression and boiling point elevation. I've been given this chemistry problem:

Acetic acid has a boiling point elevation constant of 2.93 and a normal boiling point of 118.1 Celsius. What would be the boiling point of a solution made by dissolving 100.0 grams of calcium carbonate (CaCO3) in 400.0 grams of acetic acid?

This requires me to use the equation for boiling point elevation, that is:
ΔTb = Kb · bsolute · i, or change in temperature = the ebullioscopic constant * the molality of the solution * the number of ions the solute splits into.

My question is how does one determine i for a given solute in a case like this? Thanks for any help you can give!


texts: How do you remove lumps in reagents without contaminating them?

texts:
I think desiccating the powdered reagent would help remove lumps (at least in preventing lump neoformation) but would desiccation alone collapse all lumps in a powder (say KCl as it lumps easily), or would the lump formation itself prevent desiccation of the molecules at their core?

What about vacuum?

The challenge is in doing it without adulterating the reagent and I'm not sure how to do that.

Ideally I'd vacuum heat the powder inside of a glass grinder but the budget for this is probably far beyond my means.


texts: When boiling water, how is evaporation rate affected by the surface area of the container?

texts:
Imagine two pots boiling on a stove. One is tall, while one is wide. Both contain the same volume of water.

What will be the difference in the rate of evaporation between the two containers?


texts:
How do I solve this question?

My thinking is this: since O2 is not a reactant in any step, and since the reaction rate depends only on the reactants, increasing the concentration of O2 does not affect the rate of the reaction.

Is my thinking correct?


texts: What can we say about the Gibbs free energy if it decreases or not?

texts:
[Sorry if the question looks trivial but I have thought about it for days and red a number of books all with no success.]

In almost every thermodynamics book that has something to say about chemical reactions there is a proof for the fact that at constant pressure and temperature the process is spontaneous in the direction in which the Gibbs free energy decreases. In some of the books it is also remarked that this conclusion is for when there is no "additional work" (beside the work of pressure in expanding the system), if there is an additional work then except for $dG=0$ the reversible process will yield into that additional work gaining its maximum value:

\begin{align}
\text{The only work is expansive:}\qquad & dG\le 0\\
\text{There are some additional works present:}\qquad & dG\le \delta W_{\text{additional}}
\end{align}

In this regard I have a question:
 When we have some additional works there in the problem (like electric work in an electrochemical cell), so that the second inequality holds and the maximum work is assigned to $dG$ as $dG=\delta W_{Add,Max}$, why still we feel free to use the first inequality and claim $dG$ should be negative?

In the case of electrochemical cells we have: $\delta W_{E,Max}=-n\,F\,E_{cell}\,d\zeta$ wherein $\zeta$ measure the advancement of the reaction. So we would obtain in a reversible (i.e. infinitely slow) reaction $\Delta_rG=\frac{dG_{p,t}}{d\zeta}=-n\,F\,E_{cell}$. But all the books then state that since the reaction is spontaneous in the direction in which $\Delta_rG\le 0$ so we would obtain $E_{cell}\ge 0$, while we know the inequality $\Delta_rG\le0$ is obtained from $dG\le0$ which doesn't hold here.

My question in other wording reads like this. Does the electrochemical cell problem involve an electric work or not? If "yes" then from where do we know the Gibbs free energy should decrease? And if "no" then from where do we obtain the equality $\Delta_rG=-n\,F\,E_{cell}$?


texts: Residual hydroxyl groups in silicone resins

texts: Silicone resins are solutions of branched-chain siloxanes containing residual hydroxyl groups. What is meant by "residual hydroxyl groups"?


texts:
I understood how to find aromatic nature of single aromatic rings (like benzene) or that of combination of rings which are independently aromatic, such that the electrons of one ring do not enter into another ring (like biphenyl).
However I don't have much clarity on finding the aromatic nature if electrons from 2 or more rings can delocalise into each other.
Like biphenylene

(Image Source:pubchem)
If I only look at the central ring it seems to be antiaromatic. However there can be resonance throughout the entire molecule that can cause it to be more anti aromatic. Also the top and bottom rings might have aromatic character on resonance in individual rings too. These are just my guesses so I don't know what is the actual nature of the compound, but I didn't understand why this compound would be stable if it is associated with some antiaromatic character? Please elaborate on this aspect


texts:
It seems that every website on sexual health advises against using oil-based lubricants with condoms. It is claimed that "oil breaks down latex". One source claimed that a latex condom completely breaks down in only 60 seconds. It made me curious, so I made an experiment.

I took a piece of rubber latex condom and soaked it into regular canola oil I found in the kitchen. I checked the condom after 1 minute, nothing changed. So I let it soak for about 5 minutes more, and then 5 hours more, still nothing. It was able to hold a large amount of water without leaking or breaking.

So I am wondering, is it really true that oil degrades latex? What sort of chemical reaction is supposed to happen? What properties of the latex material and the oil influence this reaction?


texts: Hybrid thin films containing azobenzene with reversible photoresponsive behavior

texts:
I am going to prepare hybrid thin films containing azobenzene with reversible photoresponsive behavior. I have read about different combinations of inorganic layers such as layered double hydroxide (LDH) with azobenzene molecules.

However, I can't understand the photocatalytic role of the inorganic portion in the isomerization of azobenzene. Can insulators be used as the inorganic part instead of semiconductors (if I consider LDH as the doped composite)?


texts:
I vaguely recall having heard that drinking too much water can, over time, prove fatal to the human body.

Nothing special about the water; not distilled or de-ionized or anything … just plain ol' water.

Now the reason that accompanied this "fact", was that drinking too much water serves to dilute, and thereby, disrupt the electrolyte balance in all (living) body tissue. This in turn, messes with the sodium-potassium pump present in cells leading to loss of functionality of cells.

Now I can't seem to find the source of that information, but I do recall it wasn't particularly trustworthy.

So what I want to know is:

Is it true, that drinking a lot of water can be fatal?
If so, is it because the electrolyte concentration inside and outside cells are "diluted"?
Does this affect all (living) tissue equally?**

Edit:

I fail to see why this was put on hold as a personal medical question. I vote to reopen this on the grounds that it does not:

a) Ask for advice on treating water intoxication

b) Suggest, promote or request, in any way, alternative forms of medicine.


texts: solve steady state of simple product reaction

texts:
consider these biochemical reactions (simpler than usual michaelis-menten setup):

$E + S \rightarrow^{k_{f}} ES$

$ES \rightarrow^{k_{r}} E + S$

$E$ and $S$ reversibly make $ES$. the forward/reverse rate constants are equal: $k_{f} = k_{r} = k$. how can you solve for steady state concentration of $[ES]$ given initial amounts $[E]_{0}, [S]_{0}$ and assuming $[ES]_0 = 0$?

$d[ES]/dt = k[E][S] - k[ES] = 0$

rate constant cancels:

$[ES] = [E][S]$

then $[E] = E_{t} - [ES]$ where $E_{t}$ is total enzyme concentration. by substitution:

$[ES] = [S]([E]_{t} - [ES])$

$[ES] = [S][E]_{t} - [ES][S]$

$[ES] + [ES][S] = [S][E]_{t}$

$[ES] = \frac{[S][E]_{t}}{1 + [S]}$

but if $E_{0} = 10, S_{0} = 5$ then $[ES] = (5 * 10) / (5 + 1) \approx 8.3$ but the right answer is closer to 4. what's wrong with this?


texts: Is it possible for one of reactants to deplete before achieving equilibrium

texts:
Consider the following reaction where $\ce{A}$ & $\ce{B}$ reacts to produce $\ce{C}$ & $\ce{D}$.

$$\ce{ A(g) + B(g) <=> C(g) + D(g)}$$

Is it possible for $\ce{A}$ or/and $\ce{B}$ to run out before equilibrium at some given starting moles of $\ce{A}$,$\ce{B}$,$\ce{C}$ & $\ce{D}$.


texts: Why does NH3 cause pairing in case of some metal complexes and doesn't in case of others?

texts:
I was met with a question that required me to find which complex is an outer orbital complex, and two of the options included $\ce{ [Ni(NH3)6]^2+}$ and $\ce{[Co(NH3)6]^3+}$,
I want to know why does $\ce {NH3}$ acts as a strong field ligand and cause pairing of electrons in d orbital in the case of $\ce{[Co(NH3)6]^3+}$ but acts as a weak field ligand and doesnt cause pairing in the case of $\ce{ [Ni(NH3)6]^2+}$ (hence making it a outer orbital complex)?
I know that $\ce{NH3}$ lies in the middle of spectrochemical series, so how do I identify if it will cause pairing in a complex or not?


texts: How is the crystal direction important for etching silicon surfaces?

texts:
I am a student of masters study with a background only in electrical engineering, but I have studied Miller indices and crystallographic planes and directions, personally, to help myself understand the process of silicon etching which is required in my current course of study. But, I am unable to understand the following written in my text book:

  "When Silicon is etched anisotropically, i.e. depending on crystal direction, and a {1 0 0} surface direction is used, cavities will result which have the same {1 0 0} orientation at the bottom and are determined laterally by {1 1 1} surfaces. The reason is that {1 1 1} surfaces are etched off using a minimal etch rate and this way becomes the most resistant"

Could someone please help me understand this concept.


texts: Are clathrates and interstitial compounds the same thing?

texts:
In the book$\ce{^{[1]}}$,  it's given that clathrates are compounds in which gases are entrapped within cavities of crystal lattices of certain organic or inorganic compounds. Interstitial compounds are formed when small atoms occupy positions in the interstices of the metal lattice. So I'm not sure what is the difference between the two? Also it's given that only Helium forms interstitial compounds and Argon, Krypton and Xenon forms clathrates. Could anyone help me understand the difference between the two?

Reference

Pradeep, New Course Chemistry, Class XII, Vol. 1


texts: Why do carboxylic acid derivatives show a more upfield shift than carbonyls in 13C-NMR?

texts: The prototypical 13C NMR shifts of carbonyl carbons is in the range 190–200 ppm, however, carboxylic acid derivatives have a 13C NMR shift in the range 160–180 ppm instead. What structural factors cause this shift upfield? Shouldn't the carbon in the carboxylic acid be more deshielded than the analogous carbonyl, since there are two oxygens instead of one?


texts:
The following image is taken from Wikibooks

How does isoprene polymerise to form double bonds between two monomers and in each monomer? As far as I have learned is that upon polymerisation two monomer join by a single bond and form a double bond within each monomer which can be explained by the following image:


texts: What is the difference between IPA and Ethanol in terms of solubility?

texts:
I have read an article online that says that ethanol could be used in a solvent extraction of two solids, but it also says that isopropyl alcohol could also be used, but must be used in higher concentrations. Why?

From some preliminary internet searches, I have discovered that:

"Isopropyl alcohol is a slightly bigger molecule than ethanol (Methanol is $\ce{CH4O}$, Ethanol is $\ce{C2H6O}$ and Isopropyl alcohol is $\ce{C3H8O}$) and is often cheaper to make. It is not as poisonous as methanol (an ounce of methanol can kill you and a third of an ounce causes blindness). So it is useful as a solvent in the same way acetone is useful as a solvent."

So would this suggest that if one were to use IPA as a solvent, one could use the same amount of IPA as they would Acetone?

One final question. It would be best to use 99% pure solvents (mostly free of water), however for an ethanol replacement, I have seen a product used for ethanol fireplaces where the MSDS mentions 95% ethanol and 5% 2-propanol. Would this be an acceptable substitute for 99% ethanol? Thanks a lot.


texts:
I know that to correctly assign R,S priorities I have to rotate the above figure until the H is projecting into the page (away from me). However, I don't know how to rotate the H and the rest of the molecule when the H is in the plane of the page.

When I imagine tilting the molecule back I get a see-saw shaped molecule ... obviously incorrect.


texts: How is the ΔL = ±1 selection rule derived?

texts:
I understand there are selection rules in spectroscopy and quantum mechanics which governs whether a transition happens or not. For example, in atomic spectroscopy, the total orbital angular momentum quantum number $L$ can only change by plus or minus one:

$$\Delta L = \pm 1$$

I'd like to know the derivation of this selection rule, but I dont know where to start from.


texts: Why does burning wood produce methane and other hydrocarbon chains?

texts: This post kinda helps me understand and it sounds like it has to do with pyrolysis, but I'm having trouble putting the exact reactions together.


texts: How is octane rating defined for negative values and those over 100?

texts:
Based on my reading, the octane rating for a given fuel is calculated by finding the compression ratio at which it knocks and finding a mixture of $X\%$ isooctane and $(100 - X)\%$ n-heptane which knocks at the same compression ratio. The $X\%$ isooctane is then that fuel's octane rating.

But how does this work with negative numbers or those over 100?


texts: How to calculate the mass of phosgene in the equilibrium mixture of carbon dioxide and chlorine?

texts:
Consider the reaction:
$$\ce{CO(g) + Cl2(g) <=> COCl2(g)}$$
A closed $\pu{5.69 L}$ flask containing a reaction mixture at equilibrium has $[\ce{CO}] = \pu{1.8 \times 10^-6 M}$ and $[\ce{Cl2}] = \pu{6.3 \times 10^-7 M}$. Given that the equilibrium constant $K_\mathrm{eq} = 2.9 \times 10^{10}$, calculate the mass of $\ce{COCl2}$ present in the flask.

How can I solve the question above? I thought that equilibrium constants deal with concentrations and not masses, so I'm not sure how to use it to calculate a mass.


texts: Why can't I dry/concentrate ethanol using calcium chloride ... or can I?

texts:
My (very unreliable) school textbook tells me:

  Lower alcohols form a solid derivative with certain metal salts.

and,

  It is for this reason that ethanol cannot be dried/concentrated using anhydrous calcium chloride.

Nowhere else in the book, is there any reference to this supposed reaction between a lower alcohol (ethanol) and a metal salt (calcium chloride). So I couldn't read more about this from there...

Googling wasn't much help; though I did find this paper that seems to concur with my textbook (albeit, with more detail) ... the paper is dated all the way back to 1923, so I suspect the modern Chemist's view of the matter would be different (the paper makes use of the term "alcoholate", which no longer carries the same meaning).

Question:

Does ethanol really react with calcium chloride to form some "solid derivative"?

Additionally,

Do lower alcohols (methanol and ethanol to name a few) really react with "metal salts" (textbook didn't specify, so i would use the following examples: copper sulfate and magnesium chloride)?


texts: Why does the conversion of SO₂ to SO₃ require high pressure?

texts:
The conversion of sulfur dioxide to sulfur trioxide in the contact process for the manufacture of sulfuric acid requires the following condition:

Temperature: 450 degrees
Pressure: 1-2 atm, although High pressure would fasten the reaction, creating those pressures is not economical
Vanadium Pentoxide ($\ce{V2O5}$) as catalyst
and excess of oxygen

$\ce{2SO2 + O2 -> 2SO3}$

My textbook says that high pressure favors the rate of the reaction. The reason it states is that the volume of product is less than that of the reactants.

Can somebody explain how the volume of the product being less causes high pressure to be required?


texts: How do we actually know the chemical structure of a compound?

texts:
If a compound is placed before you and you are asked to determine what it is and what it's structure is, how do you actually do that?

This might be a baby question for most of you but I am not from chemistry background and so this amazes me!


texts: we are learning about galvanic cells. I would like to know the half equations and overall equation that occurs in this lead acid cell. so far my understanding for the oxidisation section is that in a lead acid battery oxidisation occurs in lead which has the equation Pb →Pb2+. The equation for the overall reaction at the anode is Pb + SO42- → PbSO4 + 2e-. is this correct because i am confused about the sulphuric acid as i thought it was H2SO4 but a lot of sites have it as SO4 or HSO4.


texts: How to calculate the amount of aluminium that has been oxidised?

texts:
I have a sample of pure aluminium (100%), 1 kg, stored in "normal condition"
After some time the weight of sample has increased by 1%.
I assume that aluminium has oxidized to $\ce{Al2O3}$

I know the weight before and after, and my question is: how to calculate how much aluminium has been oxidised?


texts:
Is my proof valid for the formula of elevation in boiling point?

proof

By Clausius clayperon equation,
$$\ln(P)=-\frac{∆H_v}{RT}+c$$
Differentiating,
$$\frac{dP}{P}=\frac{∆H_v dT}{RT^2}$$
Approximating $dP\approx ∆P$ , $dT\approx ∆T$,
$$\frac{∆P}{P}=\frac{∆H_v∆T}{RT^2}$$
Let $∆P=P_{solution}-∆P_{solvent}$ and $T^2\approx T_{boiling}^2$ also $∆T=$ Change in boiling point,

By the formula for relative lowering of vapour pressure,
$\frac{∆P}{P}=mf_{solute}$
$$mf_{solute}=\frac{∆H_v∆T_{boiling}}{RT_{boiling,solvent}^2}$$
$$∆T=\Big(\frac{RT_b^2}{∆H_v}\Big)mf_{solute}$$
But i don't know how to proceed further, can anyone help?

The actual formula differs from mine as,
$$∆T=\Big(\frac{RT_b^2}{∆H_v}\Big)molality_{solute}$$


texts: pKa and pH behaviour of a drug lignocain

texts:
Lignocain is a weak base with pKa of 7.9. if injected into an acidic ( low pH medium or tissue ) it does not act adequately. Reason probably is that it becomes more dissociated and ionized drugs donot penetrate tissues adequately.
But according to relationship between pH and pKa in this forum it is given to understand that substances with high pKa in low pH solution get protonated or undissociated ? why the difference in interpretation?


texts: Does the lamellar structure in say a copper-silver phase diagram have any unique mechanical properties?

texts: For example, at lower amounts of silver the alloy gets stronger due to precipitation hardening, so in the composition as the wt% of silver increases how do the mechanical properties change? Both of them are FCC structure, so does the ductility remain the same as well?


texts: Which compound or compounds are responsible for color change in blue butterfly pea flower tea?

texts:
Blue Butterfly Pea flower tea is blue by default. Add citrus juice and it turns purple. What compound or compounds are responsible for this reaction to change in pH?

Wikipedia doesn't say, nor can I find any source on the internet that does.


texts: How can aluminium oxide be called an acid?

texts:
Aluminium oxide is amphoteric. It is easy to see that it is a Brønsted-Lowry base through the following reaction:

$$\ce{Al_2O_3 + 6HCl \rightarrow 2AlCl_3 + 3H_2O}$$

The aluminum oxide splits and the oxygen accepts a proton, forming water.

But what about the reaction with a base? In my textbook, they say:

$$\ce{Al_2O_3 + NaOH \rightarrow 2NaAlO_2 + H_2O}$$

Now, the textbook claims that Aluminium oxide is an acid merely because it reacts with a base to form a salt and water, as is characteristic of a neutralization reaction.

But I'm not satisfied with this definition. I mean, acids aren't defined as 'things that neutralize bases', we have well-established definitions for them.

I tried to figure out for myself how this could be. Clearly, the Brønsted-Lowry theory cannot be applied here since the compound in question has no protons to donate. Therefore, the only alternative is the Lewis concept. I cannot see how that is applicable in this case.


texts: Looking for solubility kinetics of zinc chloride hydroxide monohydrate

texts: $\ce{Zn5(OH)8Cl2.H2O}$ is a crystalline solid insoluble in water. Often used as nutritional supplement. Preparation and chemistry of zinc chloride hydroxide monohydrate is known. I am looking for some additional data such as solubility or solubility kinetics basically in anything. I wasn't able to find any valid data.


texts: Magnitude of Lennard-Jones force evaluated with molecular dynamics simulation

texts:
The intent is to evaluate the error source of a molecular dynamics (MD) simulation which is only based on the Lennard-Jones interaction between noble gases (helium in this case). What is the magnitude of the force?
For reference: $\varepsilon = \pu{1.49E-22 J}$ and $\sigma = \pu{2.967E-10 m}.$
The equation used to calculate the force is:
$$F = 4\varepsilon\left(\frac{6\sigma^6}{r_\mathrm{abs}^7} - \frac{12\sigma^{12}}{r_\mathrm{abs}^{13}}\right) \sim \pu{E-13 N}$$
Combined with the mass of helium this leads to an acceleration which seems to be too large. Would the above make sense?
Our step size is roughly $\pu{5E-3 s}$ and the velocity has a magnitude of $\pu{E13 m s^-1}.$ This is our problem at the moment because those values are obviously too large. We are using the Verlet algorithm.


texts: Some substances like copper sulfate for example have vivid colors. But why is water transparent? Does it not emit any visual light from the electromagnetic spectrum?


texts: Should an entire compound or just the redox-active element be written in redox pairs?

texts:
For oxidant/reductants and conjugate pairs, for example $\ce{MnO2 -> Mn^2+}$, do we write $\ce{Mn^4+}$ or $\ce{MnO2}$ as the oxidant? Websites conflicts what my text book says, because it appears that my text book would write the conjugate pair as $\ce{Mn^4+/Mn^2+}$ which implies that it considers $\ce{Mn^4+}$ is the oxidant not $\ce{MnO2}$.

I just realised my example wouldn't work for what I was trying to say since $\ce{MnO2}$ does not exist in ionic form. But using a compound that did exist in the ionic form, would I be saying that the oxidant is the entire compound or the ion that has a change in oxidation number?


texts: Name of corresponding anion of a hemiacetal

texts:
If a hemiacetal is deprotonated at its hydroxyl group, what is the correct name for the resulting anion (or salt)?

I could not find anything, and assume that these compounds are probably not stable (just like most hemiacetals themselves), but I'd still be interested what's the right nomenclature here - something with -ate, -alkoxide, or the like?


texts: Is there a reaction happening between Coconut Oil & Hydrogen Peroxide?

texts:
On a whim, I mixed together some coconut oil and drug store (3%) hydrogen peroxide and washed my hands with it. It definitely felt less greasy than pure coconut oil, left my hands feeling clean and soft :)

Did any chemical reaction occur between the coconut oil and $\ce{H2O2}$ to make a new compound? My guess would be, since Coconut Oil is mainly lauric acid, small quantities of peroxylauric acid may have been produced?

I only had high school chemistry so I could be wrong. Just my guess. Anyone know for sure?


texts: Does carbon monoxide form or carbon dioxide forms when carbon reduces metal oxide?

texts:
I would like to discuss this in context of ellingham diagrams.
When $\ce{C -> CO}$ line is below metal oxide line, CO is produced.
Similarly, in other case $\ce{CO2}$ is produced.
But when both lines are below metal oxide, is carbon monoxide produced or carbon dioxide?


texts:
I understand (more or less) that acidification of water helps in the dissociation of water into ions. Acids easily dissociate into ions in aqueous solution. So, accordingly, the hydrogen from the acid goes to the cathode and the hydrogen from the water makes a compound with the negative radical from the acid. In the process, oxygen is left alone and hence goes to the anode. I want to confirm whether this is the correct explanation.

I have been trying to find out why is copper sulphate acidified during its electrolytic refining.  I interpret  that acidifying copper sulphate makes it dissociate easily into ions but I want to know what the exact process is. It doesn't seem to me that copper sulphate may behave in the same way as water does above. Please help.

In general, I would like to understand the effect of decreasing or increasing pH on the process of electrolysis.


texts: Which has more inductive effect: an aldehyde or a carboxylic acid?

texts:
A chemistry reference book that I have been reading gives the order of inductive effect ($-I$) as follows:

While the Wikipedia page on inductive effect gives the following order:

$\ce{-NH3+} > \ce{-NO2} > \ce{-SO2R} > \ce{-CN} > \ce{-SO3H} > \ce{-CHO} > \ce{-CO} > \ce{-COOH} > \ce{-COCl}> \ce{-CONH2} >
\ce{-F} > \ce{-Cl} > \ce{-Br} > \ce{-I} > \ce{-OR} > \ce{-OH} > \ce{-NH2} > \ce{-C6H5} >\ce{-CH=CH2} >\ce{-H}$

The reference book has $\ce{COOH}$ ahead of $\ce{CHO}$ but Wikipedia has it the other way around. Which source is correct?


texts:
I know that plastic are susceptible to UV attack. They create free radicals when put under sunlight even when kept for a short time.
I'd like to know if the photo-damage will stop once it is taken away from the sunlight or will it continue the photo-damage to the plastic. Does the rate becomes very slow because of the absence of light even when there is presence of free radicals?


texts: Why are these compounds classified as metamers?

texts:
Metamers are compounds having the same molecular formula but different number of carbon atoms,  on either side of functional group.
In the above compounds, the number of carbon atoms around the ester group are 6 on each side.
So how exactly can we call them metamers


texts:
I came across this definition.

When discussing nucleophilicity we’re specifically talking about donating a pair of electrons to an atom other than hydrogen (usually carbon).  When a species is donating a pair of electrons to a hydrogen (more specifically, a proton, H+) we call it a base.

Website:

http://www.masterorganicchemistry.com/2012/06/18/what-makes-a-good-nucleophile/

Does this make this drawing of mine wrong? I labeled the base here a nucleophile even though the nucleophile is lending n electron pair to the hydrogen. Are all bases nucleophiles?  Or should I stick with the definition above? (Forgive the forgotten arrow from the bond between oxygen and hydrogen which should be pointing at oxygen's valence environment.


texts: Maximum number of coplanar atoms in difluorotrimethylphosphorane

texts:
In $\ce{PF2(CH3)3},$ what is the maximum number of atoms lying in one plane?

$\ce{P}$ is the central atom with the hybridization $\mathrm{sp^3d}.$ Two $\ce{F}$ atoms will form axial bonds with it, while three $\ce{CH3}$-groups form equatorial bonds. Each of these $\ce{CH3}$-groups has tetrahedral geometry, which means that one $\ce{H}$ atom lies in the same plane as the $\ce{C}$ central atom.
Thus, two $\ce{F}$ atoms, one $\ce{P}$ atom, one $\ce{C}$ atom and one $\ce{H}$ atom with it, totalling five atoms, lie in the same plane.
Is my attempt correct?


texts: How much heat is required to raise the temperature of 230 g CH3OH(l) from 22.0 to 30.0 ∘C?

texts:
How much heat is required to raise the temperature of $230\ \mathrm g$ $\ce{CH3OH(l)}$ from $22.0\ ^\circ\mathrm C$ to $30.0\ ^\circ\mathrm C$ and then vaporize it at $30.0\ ^\circ\mathrm C$? Use enthalpy of vaporization $\ce{CH3OH(l)} = 38.0\ \mathrm{kJ\ mol^{−1}}$ and a molar heat capacity of $\ce{CH3OH(l)}$ of $81.1\ \mathrm{J\ mol^{−1}\ K^{−1}}$.

I Used the equation $Q_\text{total} = Q_\text{heat} + Q_\text{vap}$. My answer was $88.9\ \mathrm{kJ}$.

However, it is wrong.


texts: Why don't dicarboxylic acids show hydrogen bonding in spite of the fact that carboxylic acids exist usually as dimers in polar aprotic solvent?

texts:
I have seen several examples:

The fact that maleic acid is more soluble in water than fumaric acid in spite of the fact that it must be able to show intramolecular hydrogen bonding.
trans-Cyclopentane-1,2-dicarboxylic acid is more stable than the cis form (cis form should be able to show hydrogen bonding).
o-Nitrobenzoic acid is more acidic than the para isomer.

I tried linking point 1 to acidic strength (maleic acid > fumaric acid because of hydrogen bonding in conjugate base) and point 3 to acidic strength (o-nitrophenol < p-nitrophenol)
What am I missing? Something related to the size of the ring?


texts: Say that we have an atom which is inert, or stable. How would one go about adding one electron. Is it possible?


texts: pH value of HF, hydrogen fluoride or hydrofluoric acid?

texts:
I've been looking for a source but I find different results when I try looking for an answer to this.
I'm looking for weight percentages of 1 to 10% HF (~0.5 to ~5.1M) and what their pH values are.
Now Honeywell says that around 5 to 10% it's pH is above 4.4
However if you calculate this using the $K_a$ of $6.8\times 10^{-4}$, you would get about 1.5 pH, which is quite the difference.
http://www3.imperial.ac.uk/pls/portallive/docs/1/7276108.PDF (Honeywell / imperial university)
This is just an example, because looking for these values online, for the same molar concentration, different answers are given of around pH 1 to 4.5.

So my question is can somebody explain how to properly get the correct pH values, or confirm what they are.

Also, secondary I would like to create a buffer solution with HF having a pH within the range of 4-7 (specific etching chemistry, $\ce{SiO2}$ vs $\ce{HfO2}$, not etching $\ce{HfO2}$). So other options to achieve this from stock $\ce{HF}$ (49%) with standard chemicals is also an option, however $\ce{NaF}$ is not readily available for me (mostly only access to solutions, such as $\ce{NH4OH}$).


texts: In the absence of a physical model, how can I use free software to visualize stereochemistry?

texts: In a different question, the task was to turn a wedge-and-dash representation into a Fischer projection. This involved rotation of a fairly complex molecule - either as a physical model or a mental model - to orient each chiral carbon in preparation for drawing the Fischer projection. How can you use free software to visualize this process?


texts: How to get force constants in internal coordinates in Gaussian?

texts: I have tried quite a few different ways to get Gaussian to print the force constants in internal coordinates. If the size of the molecule is small then it prints both the internal hessian and Cartesian hessian in the log file on using Iop(7/32=5), it outputs only the Cartesian hessian without the Iop command. But if the size of the molecule is large then it stops printing the hessian in the .log file. Though the Cartesian hessian is always printed in the checkpoint file. How do I get the internal hessian? I am also using #p to get Gaussian to write everything in the log file.


texts: Are Cubic Equation of states applicable to Liquids?

texts: I was just going through a graph of isotherm given by cubic equation of state and noticed that isotherms passes trough the subcooled liquid region. Are these equation applicable to liquids?


texts: Are there examples of UV-Vis emission from charge-separated states? The cases I have encountered have only absorption. Is the recombination process of a nonradiative kind by necessity?


texts: When reactants are in their transition state, can they go back into their reactants form instead of progressing to form the products? I don't see any reason why the reaction has to keep progressing forward.


texts: Why is there carbon lining on the steel vessel in Hall Heroults process?

texts:
I read This answer, and completely understand that why graphite anode is used , but I have read that the vessel acts as the steel cathode but with lining of carbon. What is the need of this carbon lining ?
And this in turn raises the question , what actually is the cathode , steel or carbon ?
Thanks !!


texts: What research methods can I use in identifying Aluminum in a solid sample?

texts: I do have a cube of solid aluminum. But I need to verify that it is really Al to validate my research. What simple scientific techniques do you recommend?


texts: What is the process or material that can enhance the conductivity of the graphene oxide?

texts:
I am doing a research and experiment on using Graphene oxide for deicing. My purpose is to coat graphene oxide on the surface of the ship in the north and south pole where large amount of large size ice cubes and icebergs are present. So when voltage is applied to it, it can generate a large amount of heat to melt the ice but the amount of heat must not be significant enough to vaporize the water to steam.

So, the problem is: As you know graphene oxide has a very high resistance. So there must be some process or material that can enhance the conductivity of the graphene oxide. What is it? In other words, is there a process that can enhance the conductivity of graphene?


texts: What causes oxygen cylinders to explode when in contact with oil (oiled cloth)?

texts: Perhaps I did not put it correctly, but from the welders I know that if you leave the oiled rag on the cylinder valve, it can explode. At least, I saw how greasy oily rags that just lay in the trash can are smoldering. It is interesting to me to understand the principle of this phenomenon: whether it depends on the amount of oil, oxygen, pressure in the cylinder. If possible, I would like to see the chemical reactions occurring.


texts: Where do the electrons that are released in the sun go?

texts: I've heard that electrons are released from the clutches of nuclei in the plasma state that is present in the sun. My question is: Where do these electrons go?  Do they go to the product nuclei of the nuclear fusion reaction in sun (ie. He)? Or do they remain on the surface of sun?


texts: What are the most potent hydrogen peroxide decomposition catalysts available to an amateur?

texts:
Some months ago I was playing with $60\,\%$ $\ce{H2O2}$ and unknowingly I used a silver spoon to transfer the liquid from a container, and the peroxide immediately started bubbling (it did look and sound like violent boiling) around the spoon.
Are there solids or thick liquids available to an amateur that are even more potent in catalysing the decomposition of $\ce{H2O2}?$


texts:
I've known that hybridization in distorted geometries is not exactly $sp^3$ or $sp^2$ or whatever. For example, $\ce{PH3}$ has nearly pure $p$ orbitals in the $\ce{P-H}$ bond, and the lone pair is in a nearly pure $s$ orbital.

Basically, since hybridisation is an addition of wavefunctions, instead of a perfect symmetrical addition of the kets, we get something else.

While answering this question, I realised that it's not that easy predicting the numbers.

Take the same image of $\ce{B2H6}$:

At first, seeing the 97°, I thought "well, the inner $\ce{B-H}$ bonds will be almost pure $p$". But, with that, I couldn't figure out where the 120° came from, because that is for perfect $sp^2$.

I then realised that I was being stupid and it wasn't that simple--just because you have a 120° doesn't mean pure $sp^2$. But, I was at a loss trying to find out approximate hybridizations for $\ce{B2H6}$.

How does one generally go about predicting such "nonuniform hybridizations" if one knows the bond angles?

Approximations are OK--I believe the exact mixture ratios will require some knowledge of the exact wavefunctions.


texts:
If methacrylic acid (2-methylprop-2-enoic acid) is reacted with first $\ce{BH_3/THF}$ and second  $\ce{H_2O_2/HO^{-}}$ then $\ce{OH}$ group is attached at less subtituted carbon.

But if it is treated with $\ce{CH_3COOH}$ in the second step, what is the end product?


texts:
In describing proteins, I've written "the proteins detached from the [Ni-IDA] matrix and were eluted from the column"

Should I use "were" or can something simply "elute" ?


texts:
What would happen if (E)-4-Phenyl-3-buten-2-one, shown above is nitrated, and is this compound more or less reactive than benzene?

My Attempt: By drawing the resonance structures of the above compound, I noted that the functional group withdrew electron density from the benzene ring. This means that this compound would be less reactive than benzene; my book agrees with me on that.

However, I stated that the nitro group would be added to the ortho or para positions, due to the fact that the sigma complex created is more stable due to the resonating effects of the double bond in the functional group. On the other hand, nitrification at the meta position would result in only three resonance structures in the sigma complex, resulting in a less stable compound. However, my book states that because the functional group is a deactivating group, it is a meta-director, without any further explanation. While I understand this rule is true in the general case, why does this rule still apply in the above compound, rendering my answer wrong?


texts: nomenclature of some organoselenide moieties

texts:
what are the structures of these selenide moieties : selenenylate, selenolate ?

Can anyone tell the difference between the two in the terms of if they are anions or cations , electrophiles of nucleophiles.


texts:
Here is my second question, I know 1000 grams of water is 1 liter. But does the density affect the result? What if the substance is mercury?

When you add seed crystal in to a supersaturated solution, the solute comes out. Does this make it saturated? Is what came out the extra solute that make it supersaturated? Or is it all the solute? This is my first question.


texts: why does the gap between the energy levels of a hydrogen atom keep decreasing as we move further and further away from nucleus?

texts:
why is the gap between the first two orbits greater than the gap between second and third orbit?
shouldn't the gap keep decreasing as the radius keeps increasing? Can someone explain this ?


texts: How does X-Ray Crystallography determine the components (as opposed to the structure) of a molecule?

texts:
Thanks for some online resources (i.e. here) I have an understanding of what X-Ray Crystallography does.
By blasting X-Rays at a crystal and recording the scattering patterns on a plate behind the crystal, it becomes possible to determine the shape of the molecule in the crystal.

Where I'm confused though is in diagrams of protein molecules mapped out by x-ray crystallography, scientists are, incredibly, able to map out extremely complex structures. But what I don't understand is, how are they able to determine which atoms, or other molecules, they are seeing in the structure?
How do they know which part of the structure is which amino acid? Which part is hydrogen? Which part is nitrogen? Etc. I don't see any way of determining this from a diffraction pattern on a plate.


texts: Why does water splash if you put it into a hot pan?

texts:
I had kept my tea pan on the stove (At high)for about 30seconds . I was making tea and getting the water to put in the tea pan. There was nothing in it before that .After that , I quickly poured some water in it and boom.
The pan kind of like jumped out of the stove. The water from the pan instantly became steam and some droplets of water touched my kitchen ceiling.
The scene looked like a bomb exploding. As a single droplet of water just touched the pan , the pan just went of control.
Also , you hear a very noisy sound if you do it.
What could be reason for this little amount doing such a reaction ?
Yes, I do not advise kids to do without parents or some elders support.


texts: What is the difference between nuclear fission and nuclear fusion?

texts: I always mix up the definition of nuclear fission and nuclear fusion. So, what is nuclear fission and nuclear fusion, and an example for each?


texts: Does pH affect physical property of agarose and poly(acrylamide) gel?

texts:
We want to change pH in hydrogels of agarose and poly(acrylamide) by soaking into an acidic solution after gelation on pH 7.0.

Then, the physical property is changed? Now, we consider the condition of pH range from 7.0 to 4.0.

Please answer, and if you could, please inform the important reference.

Best, regards.


texts: When I heat up a balloon, does the air inside increase in pressure as well as volume?

texts: When I heat up a balloon, does the air inside the balloon increase in pressure as well as volume?  I thought pressure and volume were inversely proportional?  Or does pressure and volume increase as temperature increases?


texts: What ratio of bicarb to vinegar do I need in order for the result to be pH neutral?

texts:
This question stems from one I just asked over at Seasoned Advice, where my recipe tasted decidedly off because the pH was wrong.
The recipe called for $\pu{16 g}$ bicarb of soda (sodium bicarbonate, $\ce{NaHCO3}$) and $\pu{15 g}$ of vinegar (mine was 5% acidity, and I assumed a density of $\pu{1 g ml-1}$). I just googled the corresponding pHs of these two, and apparently vinegar is more acidic than bicarb is basic: vinegar has a pH of 2.4–3.4 depending on concentration, and bicarb is pH 9.5.
How can I calculate whether I put too much vinegar or too much bicarb into my recipe? The ratio in the recipe is almost $1:1$.
What ratio in grams do I need of bicarb vs vinegar in order for the result to be neutral? I know there are other contributing factors to the pH in the recipe but I just want to focus on these two first. Assuming the vinegar is 5% which mine was.
Edit:
So I found the explanation for the chemical reaction between bicarb and vinegar here. Relevant bit:

$$\ce{CH3COOH + NaHCO3 → CH3COONa + CO2 + H2O}$$
$$\frac{\pu{1 g}\;\ce{NaHCO3}}{\pu{84.0068 g mol-1}} \times \frac{1}{1} \times \pu{60.0522 g mol-1} = \pu{0.715 g}\;\ce{CH3COOH}$$
What this formula tells you is that every gram of baking soda requires \pu{0.715 g} of acetic acid. But the remaining problem is that vinegar is not pure acetic acid.  In fact, most vinegars vary from 4% to 18%.
Using those numbers, you would need somewhere between $\pu{0.715 g}/0.04 = \pu{17.9 g}$ and $\pu{0.715 g}/0.18 = \pu{3.97 g}$ of vinegar, for each gram of baking soda.
If you're lucky you can get some vinegar with the percent acetic acid listed on the label, then you can substitute that number into the equation above to determine how much vinegar you'll need.

So if I plug in my 5%, I get $\pu{0.715 g}/0.05 = \pu{14.3 g}$ vinegar for $\pu{1 g}$ bicarb.
Yikes! This is way more than $1:1$. But I'm not sure if it answers my question. Is the result, $\ce{CH3COONa + CO2 + H2O}$, pH neutral? If yes, then my vinegar does hardly anything to cancel out the base, is that right?
Edit 2:
Okay so according to Wikipedia, $\ce{CH3COONa}$ is a base. So even though my reaction formula shows what happens when all the bicarb/vinegar is used up, the result is not neutral (how much does the water and carbon dioxide contribute to bringing the pH down?). I need more acid to make my sodium acetate neutral (or at least neutral enough to be palatable?). This means that the needed ratio is higher than 14:1!? So almost certainly way too much bicarb?


texts: How to assign E/Z configuration according to the Cahn-Ingold-Prelog rules when subsituents differ only by stereochemistry

texts:
I stumbled-upon this compound:

I'm wondering how to determine the configuration of the double bond. Is it E or Z? How do I decide on the priorities when the substituents can only differ in the configurations on the chiral centers?


texts: How is dioxygen stabilised by coordination to haemoglobin?

texts:
I wonder how the binding of $\ce{O2}$ to a molecule of hemoglobin stabilizes it to the extent that I can carried around the body with the risk of it being involved in oxidation reactions minimized. The same applies to hemocyanin.

I am looking for an answer invoking orbital interactions, back-bonding etc.


texts: Does carbonation permanently increase the acidity of soda water?

texts:
If you carbonate water, and then expose the resulting soda water to the atmosphere and wait until it goes completely flat, will the (former) soda water end up more acidic in final equilibrium than water that was never carbonated and is also exposed to the atmosphere?
(Assume that both the water that was and was not carbonated are exposed to the exact same atmosphere, so that (a) they end up at the same temperature, and (b) the tiny addition to the level of atmospheric CO2 released during the carbonation process itself doesn't have any differential impact between the two waters.)
I understand that the soda water will be significantly more acidic than the flat water while it's still bubbly, because of the carbonic acid formed by the water and the injected pressurized CO2. I also believe that both waters will end up slightly acidic (although not as acidic as the soda water while it's still bubbly) because of the (modest) partial pressure of atmospheric CO2 in contact with both waters. My question is whether the high concentration of carbonic acid introduced into the soda water during the carbonation process permanently changes the equilibrium acidity of the water.
I'm also curious whether the answer would be different depending on whether you start with pure distilled water vs. "realistic" tap water, where the presence of impurities might somehow change the story.
My strong physical intuition is that the flattened (former) soda water will eventually "forget" about the carbonation and both waters will end up at the same equilibrium acidity, but some chemist friends disagree with me.


texts: New finding in cobalt compound that absorbs oxygen - is it really a breakthrough?

texts:
Very recently Chemical Sciences published results of the discovery of a new cobalt compound that can absorb oxygen at presumably a higher capacity than what has been achievable before. The paper is here. I don't have access to the full publication, and since I'm not a chemist I don't really follow the abstract too well. But from the popular news there are claims that 10 liters of the compound can absorb "a whole room of oxygen". Not very quantitative.

So my main question - is this really a breakthrough in terms of absorption capacity? And to what degree?

Also - how can the absorption/release of oxygen be controlled?

Edit: I found a link to the full article here.


texts: How to determine fire hazard of heating ethylene glycol to dissolve borax and boric acid

texts:
I am looking to replicate instructions provided in the last paragrph of this article that requires dissolving borax (Sodium Tetraborate decahydrate ($\ce{Na2B4O7·10H2O}$)) and boric acid in ethylene glycol, for reasons of practicality and cost efficiency supplied in the impure form of concentrated automotive anti-freeze.

For reasons out of scope of this question I've modified the ratio provided as follows:

5 kg anti-freeze
2.5 kg Sodium Tetraborate decahydrate
1 kg Boric acid

In order to dissolve the borax completely it is necessary to boil off the water of crystallisation plus any water impurities in the anti-freeze.

While I have water in the system, the temperature of the mix is expected to be stable at around 100 °C, but once the water is removed the temperature will rise to potentially dangerous levels if the heat source is not removed in time.

I would like to understand the risks of this operation. The flash point of (pure) ethylene glycol is, according to Wikipedia, at 111 °C. The autoignition temperature is listed as 410 °C and seems to be safely above the boiling point of ethylene glycol (it would boil off before it auto ignites). However this hazard sheet for ethylene glycol states it 'causes ignition' at 100 °C in combination with (amongst others) Sodium Chlorite (no more details given).

Can I assume that Borax and Boric acid are 'safe' as they are not listed on the hazard sheet?

Is there an (online) reference where I can find out how Borax and Boric acid modulate the flash point and auto ignition temperature of Ethylene Glycol?


texts: Which reaction occurs first when 5-hexen-1-ol reacts with sulfuric acid?

texts:
I am trying to solve this question:

Find the major product of the following reaction:

Now we could either do electrophilic addition on the alkene or do dehydration of alcohol. These two different reaction pathways yield different products. So how do we decide which reaction occurs first?
I thought that electrophilic addition could be favored because of the generation of a carbocation that could then undergo $\mathrm{S_Ni}$ reaction with the $\ce{-OH}$ generating a cyclic structure. Now if the cyclic structure were more stable than the open chain product formed by dehydration of alcohol then this reaction could be favored. But I don't know how this could be proven.


texts: Why is Omega-3 a polyunsaturated and not a monounsaturated fatty acid?

texts: If Omega-3 is a fatty acid with a single double bond at the third carbon atom from the omega end, then why is it regarded as a polyunsaturate and not a monounsaturate? Are there different Omega-3s with more than one double bond?