texts: Does partial charge violate the law of quantization of charge?

texts:
Well, we know that charge is quantized. Quoting wikipedia below,

Charge quantization is the principle that the charge of any object is an integer multiple of the elementary charge.

And we know that there is partial charge. Quoting wikipedia below,

A partial charge is a non-integer charge value when measured in elementary charge units.

Don't the above two things (and both being from the same respectable source) contradict with each other?
If yes, then which one is correct? And if both are true, then in which conditions do they follow?


texts: Entropy change of system in adiabatic irreversible process

texts: In an adiabatic irreversible process we know that q = 0. Now change in entropy is defined as q/T. So when q is zero, why is change in entropy not zero ?


texts:
How carbon nanotube sensors works?
Is the protein (or chemical compound used as part of the sensor) placed inside the tube or where is it placed? and how is the technology used to place the protein there?
In the National Geographic magazine we can read (speaking about a young inventor)

he could interweave antibodies sensitive to mesothelin into a network
of carbon nanotubes. High levels of the protein in a drop of blood
from someone with pancreatic cancer would attach to the antibodies and
cause them to enlarge, thus changing the network's electrical charge
and signaling the cancer's presence.

In the Smithsonian magazine we can read

What if he could lace a nanotube network with mesothelin-specific
antibodies, then introduce a drop of a pancreatic cancer patient’s
blood? The antibodies would bind to the mesothelin and enlarge. These
beefed-up molecules would spread the nanotubes farther apart, changing
the electrical properties of the network: The more mesothelin present,
the more antibodies would bind and grow big, and the weaker the
electrical signal would become.

link

The tubular nature of CNTs allows for internal protein encapsulation,
and also for their external coating by protein cages, affording
bottom-up ordering of molecules in hierarchical structures. To achieve
such complex systems it is imperative to master the intermolecular
forces between CNTs and proteins, including geometry effects (e.g. CNT
diameter and curvature) and how they translate into changes in the
local environment (e.g. water entropy).


texts: Hampson-Linde cycle: why does expansion need to be isenthalpic

texts:
If I understand correctly, the fluid in the Hampson-Linde cycle goes through an isenthalpic (basically a free?) expansion. For ideal gases, T would remain the same. But, depending on the substance and the temperature, the fluid may cool down.
My question is: why enthalpic? If the work (of the expanding fluid) could be used, would that not (1) lead to a bigger cooling effect and (2) useful energy output?
(I'm a beginner, so the answer might be obvious...)


texts: Is it true that the better the trial function, the better approximation for the energy in variational principle?

texts:
While studying the variational principle in McQuarrie's Quantum Chemistry, I came across the following problem: to relate the difference between an approximation $\phi$ and the exact ground-state wave function $\psi_0$ with the difference between the approximate energy $E=\int\phi^* \hat H \phi \, \text{d} \tau$ and the exact energy $E_0=\int\psi_0^* \hat H \psi_0 \, \text{d} \tau$. For instance, if I know that $\phi$ and $\psi_0$ differ by at most, say, $O(\epsilon)$ over all space, can I say that $E-E_0 \approx O(\epsilon)$?
It is intuitive to think that the better approximation $\phi$ is, the better the energy approximation gets, but I cannot prove this.
Without loss of generality, suppose $\phi$ and $\psi_0$ normalized. By writing $\phi$ as a linear combination of $\psi_n$, we get
$$
\phi=\sum_{n=0}^{\infty} c_n\psi_n
$$
such that $\sum_{n=0}^{\infty} c_n^* c_n=1$.
Therefore
$$
\hat H \phi=\sum_{n=0}^{\infty} c_n\hat H\psi_n = \sum_{n=0}^{\infty} c_nE_n\psi_n
$$
Hence $E=\int\phi^* \hat H \phi \, \text{d} \tau=\sum_{n=0}^{\infty} c_n^* c_nE_n$.
From here, the author shows that $E \geq E_0$, but how can I estimate the difference between the approximate energy and the exact energy?


texts: Why is the ionic product for water $10^{-14}$?

texts:
Why is the reference value of $K_w=10^{-14}\ \mathrm{M}^2$, such that $[\ce{H+}]= 10^{-7}\ \mathrm{M}$ and $[\ce{OH^-}]= 10^{-7}\ \mathrm{M}$ for pure water at $20\ ^\circ \mathrm{C}$?

For example, why isn't $K_w=10^{-18}\ \mathrm{M}^2$, and thus $[\ce{H+}]= 10^{-9}\ \mathrm{M}$ and $[\ce{OH-}]= 10^{-9}\ \mathrm{M}$?


texts: What causes "stringy" melted cheese (and similar behavior in other materials)?

texts:
I was wondering about this. What is the physics underlying the "stringy" consistency of melted cheese? That is, when the melted cheese is hot, and it is pulled apart, it forms strings of cheese.

This behavior also occurs with a number of other fluid substances. It seems to happen with polymer substances (like cheese which is made of proteins like casein, also plastics when melted), gums, etc. What is the technical term for this kind of behavior and what is the general mechanism by which it happens?


texts:
I know that hydrogen halides can react with each other to produce halogen halides.

As an example here is a reaction between $\ce{HCl}$ and $\ce{HF}$:
$$\ce{HCl + HF -> H2 + ClF}$$

As for the mechanism it is like this (taking into account that chlorine is hypervalent but fluorine isn't):
$$\ce{HCl + FH -> HCl\bond{...}F + H. -> H. + ClF + H. -> H2 + ClF}$$

I know that both of these are acids and that $\ce{HF}$ is weaker than $\ce{HCl}$. However with the halogen bond the negative charge on the fluorine (partial negative after the formation of the halogen bond) is more delocalized. This stabilizes the $\ce{H-Cl\bond{...}F}$ intermediate and makes the dissociation easier for the hydrogen and harder for the fluorine. And yes the hydrogen radical is very reactive but that is exactly why $\ce{H2}$ forms in this process.

But I could see some problems with this.

It would have to be in a vacuum for it to not be explosive(most reactions involving fluorine or fluorine compounds are explosive because of fluorine's high electronegativity (same reason reactions with $\ce{O2}$ burn things))
If it is in air $\ce{O2}$ could react very violently with both the chlorine and the fluorine giving you these products:
$\ce{ClO}$, $\ce{ClO2}$, $\ce{ClO3}$, $\ce{ClO4}$, $\ce{Cl2O}$, $\ce{Cl2O2}$,
$\ce{Cl2O3}$, $\ce{Cl2O4}$, $\ce{ClO6}$, $\ce{ClO7}$, $\ce{OF2}$, $\ce{O2F2}$, $\ce{ClO2F}$, $\ce{ClO3F}$
Chlorofluorocarbons could also form from reactions with carbon based compounds in the air like methane and $\ce{CO2}$.

And this is all because the halogens are very reactive.

Similar things would be true for other halogen fluorides.

So is there a more practical way to form halogen halides than reacting $\ce{HX}$ with $\ce{HY}$ where both $\ce{X}$ and $\ce{Y}$ are halogens?


texts: 2-aminoalkanes undergo haloform test (presumably iodoform test)?

texts:
I happened to find a list which showed all those compounds that gave iodoform test.It stated 2-amino alkanes  to which I was surprised as it had no ketomethyl or methyl carbinol group,but still gave an iodoform.
It would be cool if someone could help me out here.


texts: Effect of increasing nitrogen concentration in the synthesis of ammonia

texts:
For the reversible reaction
$\ce{N2 + 3H2 <--> 2NH3}$

When $\ce{N2}$ is increased, the the forward reaction is favored, increasing the yield of $\ce{NH3}$ and decreasing the yield of $\ce{H2}$. I read from multiple textbooks that the $\ce{H2}$ decreases in concentration to a greater extent than $\ce{NH3}$ increases in concentration, such that the final concentration of $\ce{NH3}$ is greater than that of $\ce{H2}$. Why is this so?


texts: Why is the para product major in the nitrosation of phenol?

texts:
When phenol reacts with nitrous acid ($\ce{NaNO2 + \mathrm{conc}\ H2SO4}$), 4-nitrosophenol and not 2-nitrosophenol is formed. I cannot understand why the para-isomer should be preferred over the ortho-isomer.

I understand the reaction mechanism proceeds by electrophilic substitution by the $\ce{NO+}$ cation, and that the $\ce{OH}$ group activates the ring, which leads to ortho and para substitution.

I don't understand why the para-isomer should be preferred over ortho?


texts: Several month ago, I soundproofed the door of my room with two sheets of lead. Can it be dangerous to live with them for many years? Can lead "decay" in some way and be inhaled? (and what happen when it oxidizes?)


texts: Can submicron mould particles go through building structures, non permeable foil paper?

texts: I read that submicron mould particles and vapours related to mould can go through walls, floors and ceilings?  Is this correct?


texts:
A useful post by @Martin indicated that probably the naming of Sweetwater town is because of the sweet tasting lead compounds in it's water.
Then my question arose. I know that the taste of any material is dependent on which tongue buds it provokes. Now, my question is, which chemical property of an element defines or is directly related or is causing the chemical property of taste? (I deliberately avoid asking this for all chemical species to prevent very broad answers, if you think you can give not-too-long answers, my question is about all chemical species.)
Note that by a responsible chemical property I mean things related specifically to an atom, like e.config.


texts: I accidently washed the Fisherbrand weighing paper (cat. 0989812A) with acetonitrile : water (1:8) to remove some sample. The weighing paper appeared to deform a little bit after the wash. I wonder if ACN:H2O mixture dissolved anything from the paper or the paper deformed just because it absorbed some water?


texts: How to distinguish mass concentration and density?

texts:
I am writing a proof where I have to mention both with density and of a material and mass concentration (mass/volume) of a material.

I am using the letter $\rho$ to represent density, and I didn't want to abuse the same symbol for concentration because it will make the whole proof much harder to follow. I would also prefer to avoid subscripts as the only distinguishable element.

What other symbol or syntax should I use to distinguish density from mass concentration of a material?


texts: Thermionic Emission Conservation of Energy

texts:
I am learning about thermionic emission and how it led to the vacuum tube. It is said that thermionic emission was a way to increase the flow of electrons from a signal (e.g. in a radio receiving a weak signal, boosted by thermionic emission). What I don't understand is how it "generates" electricity; even if the coil is heated to it's work threshold, wouldn't a coil only be able to emit as many electrons as are supplied?
Thank you for your time


texts: What is the difference between these equations for the Contact process?

texts:
Some webpages describe the contact process as this (I left out $\ce{SO2}$, $\ce{SO3}$ production):

$\ce{SO3 + H2SO4 -> H2S2O7}$

After this, it is controllable to add water to the oleum therefore making liquid sulfuric acid. However, some other sites describe this:

$\ce{SO3 + H2O  -> H2SO4}$

I am confused about what really happens in the absorption tower. I've read about the wet acid, but it states that adding water causes gaseous $\ce{H2SO4}$ to form, which is condensed.

EDIT: In the absorption tower, trioxide sulfur enters as gas, and sulfuric acid comes down as liquid. As a result the liquid comes out as oleum (first eq.). The other contact process states different: the liquid entering is 98% sulfuric acid, and 2% water, this water reacts with the sulfur trioxide (this little water avoids the heat problem), giving strengthened sulfuric acid (let's say 99.5% sulfuric acid, and 0.5% water). Still confused.


texts: Mixing of powders to make stock solutions

texts:
For a solution such as:

Luria-Bertani (LB) Broth:

10 g tryptone
5 g yeast extract
10 g of NaCl ($M = 58.44\ \mathrm{g/mol}$)

q.s. to 1 l, pH to 7.2, autoclave.

I would like to make a bulk amount of premixed powder, i.e. combine 1 kg tryptone, 500 g yeast extract and 1 kg NaCl in a big bottle, shake it and keep it on shelf. Whenever I need to make LB now I just weight 25 g of this premix and add to 1 l of water.

I’m concerned about a couple things thought. First how thoroughly it gets mixed, and second any settling of different chemicals over time. Either would cause many different batches to be messed up.

I’m wondering if anyone has experience with this and ways to avoid those two problems. I’m interested in doing this for other solutions as well. Do manufacturers who make these premixed powders re pulverize them or process them in a certain way to make it work?


texts: What bonding allows chloroaluminate (AlCl4-) to form?

texts: How is $\ce{AlCl4-}$ formed when $\ce{Al}$ only has $3$ electrons in it's outershell. It would be able to give $3$ electrons away with $\ce{AlCl3}$ for it to have a full outershell but how does it give another one away to the 4th $\ce{Cl}$? Wouldn't that cause it to be unstable as it wouldn't have a full outershell anymore? Also why would the final product $\ce{AlCl4}$ be negative? Wouldn't it be positive as it is giving electrons away?


texts: Is my electrolysis emitting compounds from additional reactions?

texts:
I am separating water into hydrogen and oxygen via electrolysis.

The electrolyte solution is sodium hydroxide (NaOH) in deionized water.

Electrodes are 99.96% pure nickel.

All gases and liquids are perfectly clear.  Even after running for hours, the electrolyte solution is crystal clear and colorless.

However, the reaction seems to be emitting something that burns the nose and throat of everyone in the room.

Is that some sort of gas from a side reaction at one of the electrodes, or is it simply bits of NaOH being carried into the air by the splashing bubbles?


texts: Internal (Z-Matrix) to Cartesian coordinates conversion

texts:
Is there any way to convert from Internal to Cartesian coordinates using simple formulas?

I have studied and implemented: INTERNAL TO CARTESIAN by Jack D. Kunitz.

But somehow the x, y and z values are not correct. I am not implementing the transformation back to the initial frame as it says, because I do not understand that step. Is that the reason for not being able to get correct answers or is this not a good tutorial or solution to follow.


texts: My father is attempting to remove the mirror from a piece of glass. We stripped the black paint from the back and exposed the shiny surface with acetone. In the past he has been able to remove aluminum mirror with lye, but that didn't react. We also attempted bleach in case it was actually silver but that didn't react either. Is there another metal that could be used to back a mirror? Are we doing anything wrong? Also adding hydrogen peroxide to the lye made the mirror bubble but no black silver oxide or white aluminum oxide.


texts:
Find the hybridization as well identify the pπ-pπ as well as pπ-dπ bonds in $\ce{ClO2}$.

$\ce{ClO2}$ has 2 $\sigma$ bonds, 1 lone pair, 2π bonds and 1 odd electron.

Hybridisation is equal to number of $\sigma$ bonds + lone pairs. Since we consider odd electron a lone pair like in $\ce{NO2}$ therefore hybridisation is coming to be $\ce{sp^3}$. There will be no pπ-pπ bonding as all p orbitals are hybridised and there will be 3pπ-dπ bonds

But this is given wrong according to my textbook. What is my mistake?


texts: How can a minor constituent of an alloy, like carbon in steel have such a profound effect?

texts: In steel that is 0.65% carbon by weight, barely one in 34 atoms is carbon (assuming no other additives/impurities). How can such an outnumbered constituent make such a big difference? Surely many of the iron atoms are not touching any carbon.


texts: How do scientists count the exact number of electrons, protons, neutrons in the atom?

texts:
An atom is very small so it is probably difficult to focus exactly on a single atom. I wonder how scientists count the exact number of electrons, protons, neutrons in an atom of a certain element.

Could you explain it?

In other words, how do we know that for example, $\ce{^{19}_9F}$ has nine protons and ten neutrons and nine electrons?


texts: Spontaneous combustion of sulfur in a steel barrel

texts:
Got some free sulfur.  Went to the site, and they put a pallet with 3 barrels on it.  One of the barrels was badly corroded, but looked like I could get it home.  I had plastic barrels at home that I could transfer the material to.

About 10 km from home I noticed I was leaving a trail of smoke.  Got in back with a shovel, and found that I had spots of burning sulfur. I smothered as best I could, got home, and spent the next two hours unloading and putting out blobs of burning sulfur.  Did a number on my truck box lining in a few spots.

The lids continued to smoke -- it was a very slow motion fire, with some form of corrosion that would burn across the surface at around an inch an hour.

The smoke smelled strong of sulfur dioxide.

The bulk of the sulfur was unchanged by all this, and I was able to get it into plastic pails and barrels with no problem.

all the barrels had been stored outside, and in the non-corroded barrel had standing water on top of the sulfur.

What happened in storage?  Since sulfur always seems to have an SO2 odour, I assume that either some bacteria makes a living processing S to SO2, or there is a very slow reaction at normal temperatures.
What corrosion product would be flammable?
Why would it start to burn when transported, instead of in the former owner's parking lot?

Sulfur combustion on barrel:

A different lid:


texts: Intermolecular forces between C and Na2O

texts:
I was trying to do an experiment called Pharaoh's Serpent and I read that the intermolecular forces between the $\ce{C}$ and the $\ce{Na2O}$ (formed in the thermal decomposition of the $\ce{NaHCO3}$) produced the "serpent" in the experiment, but I can't find what intermolecular force (if there's really one) that is.

What is the structure of this compound?

Here's a link to the experiment: https://www.youtube.com/watch?v=vQdK7gaZS0k

edited:

Here are the reactions that I can think of and I researched :

Sodium bicarbonate decomposition ( with temperature ) :

$$\ce{2NaHCO3 -> Na2CO3  +  CO2 +  H2O}$$

$$\ce{Na2CO3 -> Na2O + CO2}$$

2.Fructose complete combustion:

$$\ce{C12H22O11 + 12O2 -> 12CO2 + 11H2O}$$

Fructose incomplete combustion:

$$\ce{C12H22O11 -> 12C + 11H2O}$$

$$\ce{C12H22O11 +6O2 -> 11H2O + 12CO}$$

So , I found that the $\ce{C}$ ( produced in the fructose incomplete combustion) reacts with the $\ce{Na2O}$ ( produced in the sodium bicarbonate decomposition), composing the "body" of the "snake".


texts: Corey-Schmidt oxidation of primary alcohols

texts: Why does pyridinium dichromate (PDC) in dimethylformamide (DMF) oxidize alcohols to acids while in methylene chloride the oxidation stops at the aldehyde level?


texts: lithiation between thiophene with n-buthyllithium

texts:
I just want to know if an electrophilic aromatic substitution reaction between n-buthyllitium and thiophene takes place, where the lithium ion of n-buthyllithium acts as an electrophile and reacts with thiophene during lithiation.

Is this true?


texts: Is a fire affected or limited by ambient pressure?

texts:
Is a natural fire affected by its ambient atmosphere or more precise, what levels of pressure are possible to support fire.
By a natural fire, i define burning material that only needs air (oxygen) to burn, eg. a piece of flaming wood or plastic, rather than artificial fires like a rocket motor or a welding burner.
The pressure would be created by the injection of air in a closed chamber. Imagine hermetically sealed shipping container filled with burning wooden pallets. In normal conditions, the air/oxygen in the container would be used up very fast, and the fire would extinguish because of the lack of oxygen. Now to keep the fire alive, an apparatus would inject pressurized air (for example out of a gas canister) every time the air/oxygen level falls under a threshold value. The injection of air and conversion to other gases (eg. Co2) the pressure inside the container would rise.
Assuming an infinite supply of material to burn, would the process be influenced by the ambient pressure of the container?
I guess, at some time, the air would turn liquid, but would it, and if so how, influence the reaction?


texts: Number of intermediates and transition states in hydration of given alkene

texts:
What is the number of transition states and intermediates formed in the following reaction?

My thought:

First the alkene extracts $\ce {H^+}$ from the acid to form a carbocation. This step involves a transition state and the formation of an intermediate which is a secondary carbocation.
Next, we have an alkyl shift to this carbon, resulting in a ring expansion. The carbocation is now tertiary. Again, involving an intermediate and a transition state.
Finally $\ce{H2O}$ attacks on the tertiary carbocation. We again get a transition state and intermediate here.
A proton now leaves, which involves a transition state. The product now forms.

So I think there will be 4 transition states and 3 intermediates, but I am not sure.


texts: Particle in a box with different barriers between two molecules

texts:
I'm trying to understand different ways to solve a PIB model.

I'm given a molecule with a tetrahedral geometry and there are two related ground states - electron pair pointing up or down. I'm being asked to draw the n=1 and n=2 states in three separate cases of a finite potential barrier in the middle of the box -> VBarrier = 0, VBarrier = V0, and VBarrier = ∞. So that left of the barrier are the wavefunctions of the up orientation and right is the down orientation.

I know that for the case of VBarrier = ∞, it'll just be the same sin(n pi x/L) wavefunctions on both sides of the barrier. I don't understand how they would change for V=0 and V=V0, and why these barriers would have different heights? I'd be grateful for any help.


texts: What is a material more easily cut than shattered?

texts:
I'm currently developing a sci-fi concept for animation which partially involves a typical "the earth has been overrun by XYZ" scenario.

One of the ideas for XYZ we're thinking of is a species of intelligent crystalline beings made of diamond -- or at least a diamond like material.
These are large, arachnoid in shape and fast. They kill by piercing their pray with sharp, lance-like protrusions on the ends of their forelegs.

The problem is, thus far we've been thinking that the trick to killing these things has been 'shattering' what essentially equates to a CPU or central core suspended like the 'body' of your typical daddy long legs. Which makes sense if the material were diamond -- however we realised it might be more interesting if kinetic force like cannonballs and explosive shockwaves were less effective, and that the key was 'cutting them.'

Maybe we're bad writers, and we just can't drop the idea of our protagonist being forced to use a 'chain-blade' up close to combat one of these things, but visually we're very keen on just such a scenario. So if those among you more educated than us (i.e. all of you) could point us towards a material where 'cutting' or 'sawing' with what could be called 'super-chainsaws' is more feasible than explosives, large projectiles, or other methods of blunt force, it would be greatly appreciated.

We Do understand just such a material will probably not exist in crystalline form, thus losing the overall aesthetic we're aiming for -- but nonetheless we'd love to hear what you guys have to say in general regarding the question and context.

Thank you very much for your time.


texts: Does the Henry reaction (nitroaldol reaction) work on carboxylic-acid-derived carbonyls?

texts:
In reading about the Henry reaction in textbooks and online, I can't find any treatment of the reaction with the carbonyls of esters or acyl halides. I am imagining the reaction would be similar to the Grignard reaction, since both involve an attack on the carbonyl by a "carbanionic" species. I understand that the acyl halide and esters would be susceptible to hydrolysis, so perhaps that's the reason I can't find anything.
Has this reaction ever been performed on a carboxylic acid derivative as I have described?


texts: Let's say I have molten potassium hydroxide and then I add some Calcium hydroxide. I imagine, since there are hydroxide groups floating around, it would be energetically neutral for the calcium ions to bind to a "new" hydroxide group, therefore they should be floating freely with the hydroxide groups, becoming solvated. I can't find any empirical data; is my reasoning correct and I can dissolve a hydroxide in any other molten hydroxide?


texts:
I'm trying to study for chemistry and there's a question in my book about identifying an element based on its atomic radius. But when I looked up the value for chlorine, I found different answers from different sources:

79 pm
175 pm (from the Princeton Review)
0.97 Å
175 pm (van der Waals radius?)
79 pm

What is the correct value?


texts:
After doing some research, I found that honey's color could be a factor of climate. I am very interested in this subject and I'm a high school student so we don't have as much apparatus as you would find in a chemistry school. The color of the honey can be determined using wavelengths which means a spectrometer is required and it is not available in our school. It would be very helpful if any of you recommended me with a way from which I can carry out this experiment and measure the color of honey.

Thanks for your valuable help!


texts:
Coordinate covalent bonds are bonds on which both electrons from one atom.

But why does this happen? Some may think it is because one of the bonding atoms have strong electronegativity. But experimental evidence suggests otherwise.

For example, carbon monoxide. The EN of carbon is 2.6, and oxygen 3.4. This may lead you to think that carbon will donate a pair of electron, but on Princeton.edu:

  Carbon monoxide (CO) can be viewed as containing one coordinate bond and two "normal" covalent bonds between the carbon atom and the oxygen atom. This highly unusual description illustrates the flexibility of this bonding description. Thus in CO, carbon is the electron acceptor and oxygen is the electron donor.

Nevertheless, in some cases like NO2, it does follows that the less electronegative atom domates electron. But why??


texts: Why does only the cis-isomer of potassium dioxalatodiaquochromate(III) form?

texts:
A friend of mine performed a standard synthesis reaction of potassium dioxalatodiaquochromate(III) by adding potassium dichromate to ethandioic acid dihydrate and a little water. The synthesis instructions suggested that only the cis-form is created. When looking online about this, I found numerous dodgy documents corroborating this idea, such as this or this.

Why is this? I can't find an explanation as to why only one stereoisomer forms nor any mechanisms anywhere.


texts: Why might litmus paper and universal indicator give conflicting pH readings in an acid-carbonate reaction?

texts:
The resulting neutralised (which wasn't actually neutralised due to not realising CaCO3's insolubility) solution between Hydrochloric Acid and Calcium Carbonate, as per balanced equation
CaCO₃ + 2HCl → CaCl₂ + CO₂ + H₂O

turned red litmus paper blue, and universal indicator solution orange (repeated twice).

I performed another reaction between Citric Acid and Calcium Carbonate and I received consistently acidic results. There is a chance I might've mixed up these results though, and the Citric Acid reaction WAS the conflicting one.

I'm wondering if anyone could shed some light on why this might've happened? I'm guessing it can't be due to the insoluble calcium carbonate, as my other reaction didn't have issues.


texts: Thought process behind Rutherford's gold foil experiment

texts: In Rutherford's gold foil experiment, if he at first thought the atom looked like the plum pudding (as Thomson had said), why did he think the alpha particles would not be repelled by the positive "pudding" and that they would go straight through?  Is it because of the high energy of the emission of the alpha particles?


texts: Have I inadvertely diethyl ether peroxides?

texts:
About 1 week ago, I used diethyl ether to wash some solid products.

I dumped it in my temporary waste container, which also contains water and some other solvents like DCM.

I returned today, and discovered that my waste container is full of yellow to brown crystals, and possibly some oil of similar color.

Needless to say I didnt stick around for long to investigate or even touch anything, as I realized that I might have turned my fume hood into a minefield (ether peroxides are friction explosive).

I wilk of course E&HS at my faculty, but it's saturday so no one is around.

Is it plausible that I've made dangerous peroxides? Has anyone else done the very stupid thing which is to store diethyl ether alongside with water in an open container for 1 week?


texts: How much energy is required to make an ion?

texts: So say that I have a normal hydrogen atom (not an isotope, just regular normal hydrogen atom) and I want to make it into an ion $\text{H}^+$. Since to make an ion of that formula I need to take away an electron, it is just the same as giving the electron energy for it to transition from quantum energy level 1 to level $\infty$, so I use the energy level formula for the hydrogen atom $E_n = -\frac{1312}{n^2}$ and substitute $n$ for $1$ and $\infty$ to get $-1312 \text{ kJ/mol}$ and $0\text{ kJ/mol}$ respectively. So if I add 1312 $\text{kJ/mol}$ of energy to the electron it should leave the atom, right? But my textbook says it is wrong.


texts: ChemDraw: Automatic Caption with Number for Molecules

texts:
When working on some reaction schemes in ChemDraw, I sometimes forget to add text/captions with numbering and align it with my molecules before placing all the molecules in a reaction scheme and aligning that.

Now that I already have a scheme, adding the numbers to the molecules will either mean I have to place the numbers by hand (which would mean they are not exactly centered) or aligning the captions to the molecule. The latter option would work, but would also mean I have to redo a lot of the work aligning my scheme.

The question is then: Is there a way to automatically place a number under a molecule, so I do not have to worry about realigning everything?


texts: Exo- or endothermic? Clarification required regarding a few cases

texts:
Are the following processes exothermic or endothermic?

a) When solid $KBr$ is dissolved in water, the solution gets colder.

b) Natural gas ($CH_4$) is burned in a surface.

c) When concentrated $H_2SO_4$ is added to water, the solution gets very hot.

d) Water is boiled in a teakettle.

Attempt at solution: For a), I would say that it is exothermic, since the solution gets colder, which means that it releases contained heat to the surroundings.

b) is exothermic evidently.

c) By the same reasoning, the solution is getting very hot, so it must be endothermic since it absorbs heat.

d) Not sure about this one. I would say endothermic, because the absorbed heat makes it boil.

This is what I answered, and apparently I made atleast two mistakes. So can someone explain to me the flaws in my reasoning?


texts: Why is a Grignard reagent not protonated by chloramine?

texts:
When $\ce{RMgX}$ (Grignard reagent) reacts with chloramine ($\ce{NH2Cl}$) it forms $\ce{RNH2}$.

But why doesn't it form $\ce{RH}$ by taking a hydrogen atom from chloramine as the negative charge so developed on nitrogen will be more stable as nitrogen has high electronegativity and $\ce{Cl}$ being a electron withdrawing group further stabilise the anion.

So where am I wrong? Can anybody suggest a mechanism?


texts: Is graphite a better lubricant on the Moon than on the Earth?

texts: My book says that it is a better lubricant on the Moon because of absence of gravitational pull on the Moon. However, I also read that it's lubricant nature is because of a film of moisture or gas molecules absorbed on the surface of its layers and in vacuum, it gets dried up and would be a bad lubricant. Which is correct?


texts: Covering conformers in a molecular modelling; consider them as a static entity or work with modelling shifts as well?

texts: I am currently working with a molecular docking project, examining potential affinities of a solvent on a protein in an assay to evaluate potential error margin. The solvent is cyclohexanol (referred to as 'ligand'), and I am trying hard to wrap my head around the solution. I have a rotatable bond at the OH group, and this is quite easy to resolve by just rotating it around and trying to fit (most software does it for you, but it can be even calculated by hand, corresponds to left and middle pic). However, cyclohexanol can (theoretically) find itself in two conformations ('chair', 'boat', with latter being much less stable) within its structure (pic at the bottom for those unfamiliar). While one of them is higher energy and therefore not found as commonly in a regular situation, for all what we know, it may have much higher affinity and stability when confronted with aminoacids in the binding site, and therefore it would maybe be unreasonable to consider only the 'easiest' state should I wish to characterise potential energies of whole ligand-protein system. I did not manage to find as of now a way to model such transitions in the context of molecular docking, and I am wondering: should I just fit twice to 'protein 1', considering cyclohexanol-chair as 'ligand 1' and cyclohexanol-boat' as 'ligand 2', or is there a method used in computational chemistry I haven't thought of/managed to find? Or should I just discard the option of a much less energetically favourable 'boat' (third in the picture) ?


texts: Is it possible to convert methane and carbon dioxide to acetic acid?

texts:
Please forgive a bumbling amateur.  I have been looking up bond strengths and it seems to me that it should be possible to combine methane with carbon dioxide to make acetic acid:

$$\ce{CH4 + CO2 ->[\color{red}{?}] CH3COOH}$$

One has to break a C=O bond (745 kJ/mol) and a C–H bond (413 kJ/mol), but one gets back a C–O bond (358 kJ/mol), an O–H bond (467 kJ/mol) and a C–C bond (347 kJ/mol) so one comes out ahead.  I know that bond energies vary slightly but this doesn't sound too far out of whack.  Wouldn't it be rather nice if one could catalyse this reaction and soak up lots of these readily available gases? Could we induce some bacterium to do it for us?


texts:
I have read in my book that ,energy of atomic orbital is greater than that of molecular orbital . I know the fact that lower energy corresponds to higher stability .

But I can't figure out the reason of why does atomic orbital possess higher energy ?


texts: Is the nomenclature "primary", "secondary", "tertiary", and "quaternary" carbon atoms limited to sp3 carbon atoms?

texts:
In organic chemistry we can classify carbon atoms as primary, secondary, tertiary, or quaternary based on the number of additional carbon atoms bonded to the carbon atom of interest. The definitions in the textbook I teach from (Klein, 1st Ed. Wiley, 2011), as well as in several others I have, and from from several locations around the web, are:

Primary $(1^\circ)$ carbon atom - bonded to one other carbon atom, e.g. $\ce{HO} {\bf \color{red}{\ce{C}}}\ce{H2CH3}$
Secondary $(2^\circ)$ carbon atom - bonded to two other carbon atoms, e.g. $\ce{HO} {\bf \color{red}{\ce{C}}}\ce{H(CH3)2}$
Tertiary $(3^\circ)$ carbon atom - bonded to three other carbon atoms, e.g. $\ce{HO} {\bf \color{red}{\ce{C}}}\ce{(CH3)3}$
Quaternary $(4^\circ)$ carbon atom - bonded to four other carbon atoms, e.g. ${\bf \color{red}{\ce{C}}}\ce{(CH3)4}$

Is this labeling system limited to $sp^3$-hybridized carbon atoms? I do not see anything in the definitions that exclude $sp^2$- or $sp$-hybridized carbon atoms. Nor have I seen or read anything that explicitly excludes these atoms. However, the images in textbooks and around the web all show and discuss only $sp^3$-hybridized carbon atoms in this context. Are the following valid?

The central atom in propene $\ce{CH3 -}{\bf\color{red}{\ce{C}}}\ce{H=CH2}$ is a $2^\circ$ carbon atom because it is bonded to two other carbon atoms.

The carbon atoms in acetylene $\ce{HC#CH}$ are $1^\circ$ carbon atoms because they each are bonded to one other carbon atom.

The ipso carbon in toluene $\ce{C6H5CH3}$ (the carbon atom where the $\ce{CH3}$ is attached) is a $3^\circ$ carbon atom because it is bonded to three other carbon atoms.


texts: Does hydrochloric acid change in concentration over time?

texts:
I have new bottles of 1 N hydrochloric acid from Fisher. The acid comes standardized from the company:

  Standardized at 25 °C to pH 8.2 against sodium hydroxide that has been standardized against NIST™ potassium acid phthalate.

Will it remain standardized after opening the bottle, or do we have to standardize it regularly?


texts: Why do peroxides tend to explode with little provocation? In general, what are typical products of their explosion?


texts: Why degree of dissociation/ionisation affected by dilution?

texts:
What happens when we dilute, say, an acid which is weak, and then add water to it? What motivates or pushes it to dissociate more?

We are just adding some molecules of water, right? So, what exactly happens to a weak acid like $\ce{CH3COOH}$ so it starts to dissociate more?

Is it because of the fact that water being a polar solvent having high dielectric constant starts to split the $\ce{O-H}$ bond in $\ce{CH3COOH}$, or something else?


texts: Is there an enolate equivalent for enamines?

texts:
I'm learning that enolates are stronger than enamines are stronger than enols in terms of general nucleophilicity. Makes sense. But what I can't find any explanation for online is why the trend shouldn't keep on going past enolates. Why isn't there a name for the species of enamine deprotonated on its heteroatom the same way there is for enols? (enols -> enolates, enamines -> ?)

I would imagine this species does not exist for some reason having to do with stability. Any explanation
or reasoning would be greatly appreciated and would help me get into the subject more. Thanks.


texts:
I read that cell constant is measured indirectly using a solution with known conductivity(like KCl).
But then how was the conductivity of that solution measured? (Is it by some theoretical consideration or another accurate experiment?)


texts: Are Slater’s rule and lanthanide contraction contradictory?

texts: According to most textbook and the Wikipedia page of lanthanide contraction, the phenomenon is due to poor shielding of nuclear charge by 4f electrons. However, the σ value of 4f electrons to 6s is 1.00 in Slater’s rule, meaning that if we go through the lanthanide elements, there should be no net change in the effective nuclear charge of 6s electrons. So are they contradictory? Is it that the σ value of 4f electrons should be smaller than 1.00?


texts:
This is something that may seem small, but it bothers me … I mean really, really bothers me. The following issue will be expressed through the Brønsted-Lowry theory of acids and bases and specifically through the neutralistaion reaction of ammonia and hydrochloric acid.
When I dissolve hydrochloric acid in water, the following equilibrium reaction takes place:
$$\ce{HCl + H2O <=> Cl- + H3O+}\tag{1}$$
When I then add a base such as ammonia, $\ce{NH3}$:
$$\ce{NH3 + H3O+ <=> H2O + NH4+}\tag{2}$$
Adding these 2 equations should give:
$$\ce{NH3 + HCl <=> NH4Cl}\tag{3}$$

This implies that the first reaction produces hydroxonium ions which the second reaction uses up, hence the number of hydroxonium ions in the solution should remain the same as before the addition of the hydrochloric acid.

Now let's actually asses the implications of such a procedure. First of all, assume that the reaction has gone to completion. This implies that when I mix water with hydrochloric acid, I will get hydroxonium and chloride ions produced. Subsequently, when I add the same number of moles of ammonia as hydrochloric acid, this will react with all of the hydroxonium ions present in the solution, as is shown in reaction (2). One problem though; this isn't a full reaction. If I add the same number of moles of ammonia as hydrochloric acid, this time there will be more hydroxonium ions than there were in the solution before addition of the hydrogen chloride (this what what I guess will happen, and this is the center of my problem). So how do I become sure that the hydroxonium ions cancel out when the equations are added?


texts: Methods for dissolving Scotch/Kaptop/etc. Tape for Electron Microscopy?

texts:
The famous method for the Nobel prize in studying Graphene is the so-called "scotch tape" method. Here, one takes a weakly-bonded van der Waals-type material and peel a layer off. From that layer, another piece of tape is taped onto the original piece of tape with the layer to split it into two pieces. This is repeated until nanometer thick layers are produced.

At this point, you have a single monolayer on a piece of tape, and need to transfer it onto a grid to look at it with a TEM (transmission electron microscope). However, the monolayer is much too thin to peel off the tape, so the tape must be completely dissolved.

The question I have is: what are the best options for dissolving tape?

Obviously there are many, many variables at play here. But here are some relevant constraints:

Completely dissolves tape, leaving little sticky residue
Solvent is relatively non-reactive to inorganics, metals
Safe and inexpensive

For example, I found a question on Research Gate that suggests using an alkaline solution to completely dissolve Kapton. I wonder if there are other methods for scotch tape

Since this method for TEM preparation is so common there must be some great literature resources on this topic, so resource recommendations would be great!

I don't fully understand the mechanics of "stickyness" so a description from the atomic perspective would be useful, especially in understanding what good solvents should do.


texts: What chemicals are used in so-called urinal "odor eaters"? Do they actually destroy odors, or do they just mask them? Also, are these chemicals subject to any environmental laws or regulations?


texts: What am I assuming when I make this approximation?

texts:
Suppose you dissolve $\ce{AgBr}$ in a $1$ litre solution of M molar $\ce{Na2S2O3}$. What is the solubility of $\ce{AgBr}$?

I am given that the $\beta_2$ of $\ce{Ag(S2O3)2^3-}$ is $2.8*10^{13}$, and the $\ce{Ksp}$ of $\ce{AgBr}$ is $5.4*10^{-13}$.

So, I have the equations:

$\ce{\frac{[Ag(S2O3)2^3-]}{[S2O3^2-]^2*[Ag+]}} = 2.8*10^{13}$

$\ce{[Ag+][Br-]} = 5.4*10^{-13}$

$\ce{[Br-] = [Ag+] + [Ag(S2O3)2^3-]}$ (mass balance for $\ce{AgBr}$)

$\ce{M = [S2O3^2-] + 2[Ag(S2O3)2^3-]}$ (mass balance for $\ce{S2O3^2-}$)

How would I solve this system of equations for any $M$? What approximations could I make?


texts: What causes steel rubbing on wood to leave grey or black marks?

texts: In my own experience, running or rubbing a high-carbon steel on wood leaves a pencil-like trail. Is this simply carbon rubbing off, or is it a more complex reaction involving tannins in the wood, like another user suggested? EDIT (thanks Ivan Neretin): Or something else entirely, like iron (or its oxides) rubbing off? And to be more precise: is it lamellar hematite that rubs off and looks gray, or pure iron or a combination?


texts: Classical Least Squares in UV-Vis Absorbance Experiment

texts: How do I find the minimum number of standards needed to calibrate a spectrophotometer using CLS? We never talked about CLS in class so I'm not sure of my approach. Would 1 standard solution per analyte be enough? We'll be plotting absorbance vs. concentration then finding the residuals from the best fit line.


texts: What happened to mesoporous materials for drug delivery?

texts:
A review on the topic can be found here: Wang, S. Ordered mesoporous materials for drug delivery. Microporous Mesoporous Mater. 2009, 117 (1–2), 1–9. DOI: 10.1016/j.micromeso.2008.07.002.

So the 21st century started with great hopes for these mesoporous materials - particularly for drug delivery. After initial success it seems the research in this field has fizzled out.  I'm just curious to why there hasn't been more progress?  Thanks so much!


texts: What chemical reactions in the soil cause that smell when it rains? In particular, what reactions in the soil causes the petrichor smell?


texts: What happens when KCl, K₂Cr₂O₇, and concentrated H₂SO₄ reacts?

texts:
What happens when $\ce{KCl}$, $\ce{K2Cr2O7}$, and concentrated $\ce{H2SO4}$ reacts?

I have no idea how to approach these questions. I'd love if anybody can help me see the logic behind this.


texts: Link1 and multiple output files in Gaussian: doable?

texts:
I have recently started learning Gaussian in my Computational Chemistry class, and I have recently learned how to use the "Link1" option, in order to run multiple calculations from a single input file.

What I was wondering is: is there an option that allows the creation of multiple output files (one for each "Link1" section), thus allowing an easier interpretation of the results for each calculation?

I couldn't find anything about the problem on the manual or online.


texts:
The O's in ozone and in dioxygen all have oxidation states of 0. If this is the case, why is ozone considered to be reduced to form dioxygen (since there's no change in oxidation state)?

Would the half reaction for this reduction be $\ce{2 O3 -> 3 O2}$ ? Since there's no transfer of electrons, how would we combine this with an oxidation half reaction to cancel out the electrons transferred in the oxidation half?


texts:
I'm solving some synthesis problems for practice and I came across this one:

I thought of going for compound A to B(aldehyde) with this procedure:

$\ce{t-BuOK}$
$\ce{BH3,THF,NaOH,H2O2}$
$\ce{PCC,CH2Cl2}$

For the second path, in order to get to a lactone, I don't know what to do. I see that the carbonyl bond is moved to another carbon. I've learnt a way, in order to get an ester, is to add an alcohol $\ce{ROH}$ to an acyl chloride. But I'm so confused.


texts: If vibrational modes are quantised, why is infrared spectroscopy smooth looking?

texts:
I have heard that the vibrational energy level in a molecule is quantised. However, when looking at the infrared spectroscopy graph, the curves look highly continuous and smooth - not something I would expect from a quantised quantity.

The sharp pointy bits in the fingerprint region (on the right) make sense, given that only certain quantised frequencies would be absorbed - but the alcohol $\ce{OH}$ group seems to be able to absorb a very large range. So, why is the graph smooth when the vibrational energy is quantised?


texts:
The Correct acidic strength of the following :

But according to me pK value of 2-nitro benzoic acid should be more than 4-nitro benzoic acid because NO2 might have H-bonding  with COOH as NO2 have it in ortho-nitro phenol.

Correct me if i'm wrong and please do tell me how to identify the presence of H-Bonding.

Thanks !


texts: Which substances have the highest/lowest enthalpy of formation per gram?

texts: Which substances have the most extreme enthalpies of formation per gram at standard temperature and pressure?


texts: Could micrograms of polonium really change the viscosity of a whole teapot?

texts:
I was reading How radioactive poison became the assassin’s weapon of choice and it opens describing how

  The men eventually left, and Andrade cleared the table. As he poured the remaining tea away, he noticed that the consistency of the liquid that tipped into the sink was strange. Gooey. He couldn’t have known it as he puzzled over its weird yellow tinge, but the man who’d been sipping the tea was a 43-year-old Russian dissident called Alexander Litvinenko, and the tea itself, draining away into the London sewers, was lethally radioactive.

Later in the article it mentions the total amount he ingested was about a microgram.

Now, skipping past the part on how you wouldn't notice you are drinking gooey tea, could micrograms of polonium change the viscosity of a whole tea kettle?

It doesn't say how much he drunk, or the size of the teapot, so lets take some guesses. Lets assume he drank a very small amount of tea, say 10 mL to give us a decent upper bound on the concentration of the solution. So that would be 0.1 micrograms/mL or about 0.5 micromolar.

Could a solution in this concentration range change the viscosity of water enough for a casual observer to notice?


texts: Why do the unsaturated ketones have C-O bond weaker than saturated ketones? How it is related to resonance structures?

texts:
I am studying Infrared Spectroscopy and the book says that unsaturated ketones have a carbonyl group which has weaker bond because it's more single-bond character than single bond because it has these three resonance structures.

On the other hand, carbonyl group in saturated ketones have more double-bond character because it only has two resonance structures.

I can't really understand - why do the unsaturated ketones have $\ce{C-O}$ bond weaker than saturated ketones? How it is related to resonance structures?


texts: Why is the melting point of lactic acid higher than pyruvic acid

texts:
I have a quick question about pyruvic acid and lactic acid, which I think I know the answer too but I'm unsure.

  The melting point of lactic acid is said to be higher than that of pyruvic acid despite very similar molecular masses.

Is this because lactic acid has 2 $\ce{OH}$ groups, and pyruvate only has 1, thus there are twice as many hydrogen bonds between lactic acid molcules that must be broken for the substance to melt?


texts: Rate expression with water as one of the reactants

texts:
When finding an equation for d[A]/dt from reaction mechanisms and $\ce{H2O}$ is a product/reactant, does $\ce{H2O}$ have to be included or left out like for equilibrium constant expressions?
For example, in the reaction of carbon dioxide with water,
$$\ce{CO2(aq) + H2O(l) -> H2CO3(aq)}$$
which expression describes the kinetics correctly (assuming that the reaction above shows the elementary step):
$$ \mathrm{rate} = k_1 \cdot [\ce{CO2(aq)}] \tag{1}$$
or
$$ \mathrm{rate} = k_2 \cdot [\ce{CO2(aq)}] \cdot [\ce{H2O(l)}] \tag{2}$$


texts: Why does steric hindrance cause a d8 complex to have a tetrahedral geometry rather than a square planar geometry?

texts:
I'm currently working on a question based on two isomers of a nickel complex, where nickel exists in the oxidation state Ni(II) (i.e. has d-electron configuration d8). It has been deduced that the "normal" isomer is square planar and the "iso" isomer is tetrahedral.

The first of the two isomers (top) is the "normal" isomer and the second (bottom) is the "iso" isomer.

Apparently steric hindrance causes the "iso" isomer to be tetrahedral rather than square planar, but I am unsure how to explain this. Is it due to the bond angles causing less strain?


texts: Do Pigments, Dyes (with plastics) or Plastic Itself Exist that Appear White but are NIR transparent?

texts: I am looking to make a NIR (Near Infrared) window for a project I am working on but need it to appear white rather than the typical Reddish Black NIR window found on most remotes.   Does a dye or pigment exist that makes PMMA or PC (open to other injection moldable thermoplastics!) look white but allows NIR (specifically 940nm) to pass with low loss?


texts: I encountered this question in a competitive exam. Can furan undergo Cannizzaro reaction? I though it can only happen with aldehydes.


texts: Will an aqueous sodium hydroxide solution degrade over time?

texts: I have a chiller bath, which is attached to a 150 ton cooling unit through 4" PVC pipe. The bath itself holds around 5000 gallons of water, and is made of 304 stainless steel. It constantly circulates through the PVC into the cooling units outside via a 20hp pump. The outside cooling units are made of steel, although I do not know the exact grade of the steel. It was however built for water circulation. I use a sodium hydroxide solution to raise the pH of the water, therefore preventing rust and keeping my water clean. The problem is that I constantly have to add the solution to keep the pH at a level that is acceptable (9-11). I have watched it enough to say that on average the pH drops by about 0.3 a day. I am wondering where all my sodium hydroxide solution is going. Thank you for the responses so far, I apologize for not being more clear on the problem.


texts: Negative ions affecting galvanic cell voltage

texts:
I don't see why negative ions don't affect the voltage. I mean the electric field of a negative ion like $\ce{SO4^{-2}}$ is not like what $\ce{NO3-}$ produces that means that it should affect the overall voltage.

This is the same reason why for example for $\ce{Cu+^2}$ the reduction electrode potential is higher than for $\ce{Zn+^2}$


texts: What analytical methods are used to quantify C, O, N, and H in a sample?

texts:
A very common analytical method for detection of more than 70 elements is ICP-OES (Wikipedia page). But apparently, it's not suited for some substances (cited from this paper, section 6.2, page 12):

  The elements that are
  not usually determined by ICP/OES fall into three basic
  categories. The ﬁrst category includes those elements
  that occur either as trace contaminants in the argon gas
  used in the ICP/OES ($C$ from $CO_2$), constituents of the
  sample solvent ($C$, $O$, $H$), or as contaminants from the
  environment or atmosphere ($N$ for example). The second
  category encompasses those elements that require high
  excitation energy, such as the halogens. These elements
  could be determined with poor LOD, however. The third
  category is the family of short-lived radioactive elements
  that are commonly determined by $\gamma$-ray spectrometry.

So, apparently, when I'm working with, say carbon-based fuels, and I want to determine $C$ contents, ICP-OES would not be the method of choice, at least not the standard variety. So, what else would be the typical choice? Or are there modifications to ICP-OES, such as using very pure $Ar$, or $He$, as the plasma gas and sealing the plasma chamber from the atmosphere?


texts: Can we apply E-Z nomenclature to geometrical isomers without a double bond. For example, can we use it for cis and trans isomers of 1,2-dimethylcyclohexane?


texts: Is there a relationship between density and viscosity of a fluid?

texts:
I'd like to know if there is a connection between the two physical quantities of density and viscosity.

e.g. How can you explain low density liquids such as mineral oils have a lower density than water but far greater viscosity?
e.g.2 Instead, for honey (18% of water and 82% of sugar...) a density of about 1.4 kg/litre but a greater viscosity?


texts:
I found a relationship online between the conductivity of electrolyte and current.

$$i = F \sum_i z_i N_i = F^2 \left( \sum_i z_i^2 u_i c_i \right)\nabla\phi = -\kappa\nabla\phi \qquad \kappa = F^2 \sum_i z_i^2 u_i c_i$$

This equation is hard for me to follow.
I get what most of the variables mean and I am guessing that $\Delta\phi$ is the potential difference. However, I thought that the conductivity was also related to temperature, which I do not see in the equation.

It has been a struggle for me to find results on the internet to relate conductivity and current together. Can someone help me and tell me if this equation is right.

Also, this equation is true for dilute solutions, what will the equation be for concentrated solutions (solutions near $\pu{1 M}$)?

Also, how would you calculate the potential gradient?


texts: Using vapor mole fraction and pressure to determine liquid mole fraction

texts:
I am studying Chemistry by Zumdahl and Zumdahl (9th edition) and I have come across a question in Chapter 11 that I can't figure out the explanation for:

Liquid A has vapor pressure x , and liquid B has vapor pressure y . What is the mole fraction of the liquid mixture if the vapor above the solution is 30% A by moles?

I know that Raoult's Law tells us that the total vapor pressure is χx + (1-χ)y in this case. I also assume that the total vapor must be 0.3x + 0.7y given the other constraint of the question. This would mean the answer should be:

0.3x + 0.7y = χx + (1-χ)y

However this leads to the answer χ = 0.3, whereas the text gives the answer as 0.3y/(0.7x+0.3y)

What have I got wrong? (Also sorry for not formatting it properly but I'm a noob here and I can't figure out the equation formatting).


texts:
My interest regarding Doxazosin made me curious, what's an easy way to synthesis Doxazosin. The first part is 2-chloro-6,7-dimethoxyquinazolin-4-amine. However, I would like to find a simple synthesis 2,3-dihydrobenzo[b][1,4]dioxin-2-yl)(piperazin-1-yl)methanone in order to get Doxazosin. I tried to form a synthesis, however it looks not very effective (too many steps, etc.).

My questions:

Is there an easier method?

Are there critical errors in my synthesis?

methyl acrylate bromation
formation the 1,4-dioxane via pyrocatechol
cleavage of the methyl group with LiOH
forming an acetylchloride
piperidine

I edited/ improved the steps with the help of Zhe.


texts: Difference between aldehydes and ketones

texts:
Why are ketones and aldehydes two different categories? To me it seems like aldehydes should be a subset of ketones. Since the general formula for ketones is CnH2n+1COCmH2m+1 and for aldehydes it is CnH2n+1COH which is just the formula for ketones but with m=0.

I am not looking for an opinion, but rather an explanation behind the reasons to have two different groups. Are there any inherent differences between them in how they react with other compounds or how they are produced?


texts:
So imagine a hypothetical chemical equation

$$
A + B \rightarrow C + B
$$

It is obvious from the equation that $B$ is not consumed during the reaction. If $B$ actively take part in the reaction, if it participates in the transition state and isn't just sitting there in the environment, I classify $B$ as a Neuter Reactant.

Under these defitions I would like to know:

Is a Neuter Reactant always a Reaction Inhibitor or Catalyst?

or are there instances of neuter reactants $B$ such that their reactions $A+B \rightarrow C+B$ have a similar rates to the straight reaction $A \rightarrow C$?


texts: I know there are chemical pigments/dyes which produce an immediate reversible colour change in UV or direct sunlight. Is there a way to postpone the colour change so that it does not happen immediately but rather over a period of 30 minutes for example? Would it have to do with the concentration of dye or is it the chemicals themselves which have different colour change times.


texts:
It is said that activation energy does not change with temperature.

But I am unable to figure out why.
If we increase the temperature, the kinetic energy of the molecules will increase and they will need less extra energy and hence lesser activation energy to overcome the threshold energy barrier.

When I surfed the net, at most of the places it has been explained that increasing the temperature increases the no. of molecules having more energy and hence reaction rate is more but activation energy is same. This makes some sense but I still don't get why the activation energy doesn't decrease as the KE of an individual molecule should also increase on increasing the temperature.


texts: Which one is more acidic – 3,5-dinitrophenol or 4-nitrophenol

texts: I’m confused because in 3,5-dinitrophenol, the inductive effect is dominating whereas in 4-nitrophenol the mesomeric effect dominates. So which one should we consider for acidity?


texts: Why is ethyne and not ethene used for welding?

texts: Ethyne (Acetylene) is used with $\ce{O2}$ for welding. My question is that why is ethene not used? What properties of ethyne make it suitable for welding?


texts: How do d-orbitals interact with molecular orbitals?

texts:
I  recently stumbled upon a question asking how iron destabilizes the bonds in a nitrogen molecule. I have searched the web and my textbook for quite a while now and I cannot find a satisfactory answer. The only explanation I could muster was that the d-orbitals of the Iron atom interact with the HOMO and LUMO of the nitrogen molecule, due to the overlap of the molecular orbitals with d-orbitals.
I am not sure if this makes sense. I'd really appreciate any answer or advice!


texts: How can I tell which parts of this example drug are necessary parts of its pharmacophore?

texts:
$\hspace{10mm}$
$\hspace{10mm}$(Click image for larger version)

This picture identifies a generic drug-enzyme complex taken from an exam script. There is no name given.  One part of the exam question states:

  Propose a structure based pharmacophore for the family of drugs to which this one belongs.

I understand that a pharmacophore is the minimum structure required to exert a certain biological activity. Therefore, my answer would go something like the following:

  We would need a drug with similar steric conformities to fill the entire active site (competitive inhibition) and that has some form of interaction at either end which keeps it in place, e.g., $\pi-\pi$ stacking with Phe groups or the H-bond and electrostatic interactions with Arg.

But would that paragraph above be a viable answer? Would this drug work just as well if it didn't have the $\pi-\pi$ stacking with the Phe groups, for instance? Are the interactions between the drug and the Lys and Glu residues dispensable - maybe that region of the drug is only there for its length?


texts:
According to Wikipedia:

  A salt is an ionic compound that can be formed by the neutralization
  reaction of an acid and a base.

Are all ionic compounds salts? Are all salts ionic compounds?


texts: What reactions involving hydrazine, dinitrogen tetroxide and possibly a contaminant can produce a salt?

texts:
Hydrazine $\ce{N2H4}$ and dinitrogen tetroxide $\ce{N2O4}$ form a hypergolic fuel and oxidizer pair widely used in spacecraft including Akatsuki (あかつき, 暁, "Dawn") also known as the Venus Climate Orbiter (VCO) and Planet-C.
Wikipedia states:

Hydrazine can be monoprotonated to form various solid salts of the hydrazinium cation ($\ce{N2H5+}$) by treatment with mineral acids. A common salt is hydrazinium sulfate, $\ce{[N2H5]HSO4}$, also called hydrazine sulfate. Hydrazine sulfate was investigated as a treatment of cancer-induced cachexia, but proved ineffective.
Double protonation gives the hydrazinium dication ($\ce{H3NNH3^2+}$), of which various salts are known

A comment below the Space SE question How did salt prevent Akatsuki's insertion burn? says:

Every article I see seems to parrot the same thing. I'm guessing this is yet another translation issue (Japanese to English) and the deposits are a hydrazine reaction product... which you could call a "salt". It's an interesting failure case that I hadn't heard of, thanks for the question.

Question: Are there possible reaction products from hydrazine and dinitrogen tetroxide alone that could form an ionic assembly of cations and anions and considered a salt, or would this require some additional contaminant, perhaps water or some organic material to be involved?


texts: How would I go about making an ethyl ester from vegetable oil?

texts:
I'm teaching myself how to make lotion and a lot of lotions contain esters like isopropyl myristate or isopropyl palmitate. I'd like to make an ethyl ester from a popular skin-care oil (olive, apricot kernel, or castor).

Since there's so much controversy about using isopropyl alcohol in skin-care, I'd like to avoid that if possible. It's very difficult to find any info on the process, and the closest I could get was how to make biodiesel. All of those use methanol though.

How would I go about making an ethyl ester from these oils?


texts: Cyanogenic and Fluorine Compounds in Pharmaceutical Science

texts: I was wonder what it was specifically that make things such as Lexapro safe when it came to its Fluoride and nitrile bonds. Why doesn't Lexapro break down into cyanide? Is it just minimal because the chemical is so large it has more mass? Is it like just priming genetic code so that it will chemically metabolize into a safe compound once pharmacokinetics steps in? I know that flourine in particular binds to calcium and sodium and so I'm assuming that's the pathway it bonds to, which is good because they have a wide range of uses.


texts:
In several sources I have read that heavier isotopologues eluate earlier than lighter ones.
As explanation vapor isotope effects are given.
But this is something I do not understand. I tought in a GC column substances are separated by their different vapor pressures and the longer a substance stays in the gas phase the earlier it eluates. Heavy isotopologues have have a smaller vapour pressure and should therefore eluate later.
What I am missing?


texts: Molecular orbital explanation of why the protonation of the oxygen atom makes a carbonyl group more electrophilic

texts:
I was working on nucleophilic addition reactions to the carbonyl group (namely, hemiacetal formation) when I came across the following explanation for the use of acid catalyst and how it increases reaction rate:

  In acid (dilute HCl, say), the mechanism is different in detail. The first step is now protonation of the carbonyl group’s lone pair: the positive charge makes it much more electrophilic so the addition reaction is faster.

The reaction at hand is the following:

Ignoring the presence of the positive formal charge on the oxygen, I am trying to understand on a molecular orbital theory level why this makes sense. I'm suspecting that this somehow lowers carbon's LUMO (${π}^{*}$ orbital), which would enhance the electrophilicity of carbon.

Would someone be able to give an explanation to the enhanced electrophilicity of the carbonyl group based on molecular orbital theory?

References

Clayden, J., Greeves, N., Warren, S. Organic chemistry, 2nd ed.; Oxford University Press: New York, 2012.


texts: With which 2 of these 5 chemicals would Chlorine not react? N, NaOH, O2, NaBr, Fe

texts:
A question in a Russian EGE test asks to choose 2 chemicals out of 5 with which Chlorine does not react:

Nitrogen - I checked and it reacts
$\ce{KOH}$ -- reacts
$\ce{O2}$ -- reacts
$\ce{NaBr}$ -- reacts
$\ce{Fe}$ -- reacts

I'm at a loss. Which two should I pick then? Maybe Fe and Nitrogen, because they would be the least likely to react?

Here's the question:


texts: There is an electronegativity difference of 1.2 between $\ce{Fe}$ and $\ce{Cl}$. Then why it is covalent?


texts: Can very dilute acids exposed to air become more concentrated as water evaporates?

texts: If a very minute quantity spilled acid (e.g. $\ce{H2SO4}$, though the question would apply to other acids as well) is cleaned up with water (e.g. yielding a $0.0001~\mathrm{M}$ solution), and some of the water (dilute acid solution) is left behind, will the resulting solution become more concentrated as the water evaporates?  Would there be any danger that a drop of an initially-harmless concentration might become a visually-unnoticeable quantity of acid that was strong enough to pose a contact hazard?  Would wiping an area down with a moderately-dilute solution of a weak base such as sodium bicarbonate be an appropriate safety precaution, or would it be unnecessary if any acid droplets that might exist on a surface have been thoroughly diluted?


texts: Is cyclic ether oxidised by periodic acid?

texts:
Is the three member ring of cyclic ether oxidised by periodic acid? As this also has oxygen attached to adjacent carbon so I think that cyclic ether of three members should be oxidised by periodic acid.

I know the mechanism of oxidation of 1,2 diols by periodic acid but ain't able to relate to this question. Please help me out here.


texts: Why is cyclopropane more acidic than propane

texts: Though I found links about ring strain and other things, I actually fail to understand the exact reason for this difference in acidity.


texts: Does enthalpy equal heat when PV work is done?

texts:
The derivation that enthalpy equals heat at constant pressure goes like:

$$\begin{align}
H &= U + P_{\mathrm{int}}V \\
\Delta H &= \Delta U + \Delta (P_{\mathrm{int}}V)
\end{align}$$

If $P_{\mathrm{int}}$ is constant, then

$$\Delta H = \Delta U + P_{\mathrm{int}}\Delta V$$

We also have

$$q = \Delta U - w$$

If external pressure is constant, $w = -P_{\mathrm{ext}}\Delta V$. Then

$$q = \Delta U + P_{\mathrm{ext}}\Delta V$$

So in order for $\Delta H$ to equal $q$, we need $P_{\mathrm{int}} = P_{\mathrm{ext}} = \mathrm{constant}$. This is true when the system is open to a constant external pressure and no PV work is done. But when there's PV work done (and the temperature is still constant), $P_{\mathrm{int}}$ clearly changes, so does $\Delta H$ still equal $q$?


texts: Excluded Volume in van Der Waals equation

texts:
I was just reading over the EOS topic when where I stumbled upon excluded volume.
Although the pictorial representation of the hard sphere model clearly shows that the excluded volume is 4 times the volume occupied by molecules, but what i am not unable to understand is that why do we take the sphere with diameter equal to one of the molecules in the first place.

So, my question is that why do we have to take the whole spehere..

I guess this has something to do with viewing the molecules in 3-dimensions, but i am unable to visualize.


texts: What is the difference between reacting and dissolving?

texts: When one chemical is added to another how would we come to know whether the compound dissolves in it or reacts with it? For example $\ce{AgNO3}$ dissolves in $\ce{CCl4}$ whereas it could also have been a double displacement reaction. And what is the major difference between the two  processes at atomic level?


texts: Calculating the age by radioactive dating

texts:
The following was an example done in class, so I know the answer and (maybe?) the formula, but I still can't derive it for myself, and I would appreciate some help.

  Given a sample of biotite with $\ce{K2O} = 9~\%,~~ \ce{^{40}Ar} = 2.242~\mathrm{\mu g/g}$, find the age.

The constants given were $x_e= 0.581 \cdot 10^{-10}\ \mathrm{y^{-1}}$, $x=5.543 \cdot 10^{-10}\ \mathrm{y^{-1}}$ where $x$ is the decay constant, isotopic abundance of $\ce{^{40}K} = 0.01167~\%$, and relative atomic masses $M_\mathrm{r}(\ce{K}) = 39.098, M_\mathrm{r}(\ce{O}) = 15.999, M_\mathrm{r} (\ce{^{40}Ar}) =39.96$.

The answer shown was $2308 \cdot 10^6~\mathrm{y}$.

The formula I'm used to for this type of problem is $t=\frac{1}{x} \ln(\frac{\ce{^{40}Ar}^*}{\ce{^{40}K}} (x/x_e +1))$ but I'm not sure how to apply that given just a percentage of $\ce{K}$ instead of a mass.  I thought of just finding the weight percentage of $\ce{K}$ from the $9~\%$ (its $80.46~\%$ of the $\ce{K_2O}$, or $7.2~\%$ of the total), but that didn't work.  I'm not sure if I need to consider atmospheric $\ce{Ar}$ either.

I tried $^{40}K = .09 * .83022 * .0001167 = 8.719 *10^{-6}$ where .833022 is the weight percentage and it didn't give the correct answer.

I also tried $^{40}K = .09 * .6666667 * .0001167 = 7.002 *10^{-6}$ using the molar percentage of K, but also didn't get the correct answer.


texts: Why is diazobenzene named so and not phenyl diazobenzene?

texts: I have searched for this answer for a long while but haven't got it. Why is diazobenzene named so and not phenyl diazobenzene or something? The group with two bonded nitrogens is the diazo group. Why does the term diazobenzene refer to a molecule with two benzene rings?


texts: What is the electron dot structure of an alkyne?

texts:
I am trying to determine the electron dot structure of an alkyne like $\ce{C2H2}$.

I know that hydrocarbons with at least one carbon-carbon triple bond are called alkynes, and their general formula is $\ce{C_{n}H_{2n-2}}$, where $n$ is number of carbon atoms.

So what will the electron dot structure of $\ce{C2H2}$ look like?


texts: Does the boiling point of an aqueous solution depend on what the solute is?

texts:
Consider a situation where we have two aqueous solutions which have the same concentration (e.g. 1 M), but the solute is different. For example, one is a solution of glucose, and the other is a solution of ethanol.

I am aware that dissolving something in water can lead to changes in boiling point (e.g. elevation). But would the boiling points of these two solutions be affected in the same manner, given that the concentration of the solute is the same? Or will the exact boiling point depend on the chemical species that is dissolved?


texts: How does a change in pH affect the colour of a leuco dye in a thermal paper?

texts: I am investigating the way that a leuco dye is released in thermal paper once heated. I have understood that leuco dyes, when in their colourless state are encapsulated in an acid developer in the thermal paper. Once the paper has been heated, the leuco dye comes in contact with the acid. There is a change in the $\mathrm{pH}$ environment and so the paper darkens. Can someone please explain the $\mathrm{pH}$ chemistry that is involved?


texts: How can the solid state structure of cyclopentadienyllithium be explained?

texts:
In the solid state, LiCp adopts a polymeric multidecker structure where Li atoms are sandwiched between two Cp rings (shown in this diagram from Organometallics 1997, 16 (17), 3855–3858):

If we consider the η5-binding mode of the Cp rings, then it seems that the number of electrons around Li is more than eight. However, Li can't extend its octet. How can the structure and bonding be explained?


texts: natural staining on wood from human skin

texts:
I have a question about the dark staining that occurs on my wooden spectacle frames where they rub constantly with my skin around the ears and nose. Can anyone tell me what is causing this? And could it be reproduced artificially?

I think you can see what I'm talking about in the photo. (Excuse poor image quality).

I make the glasses, and one of the difficulties is finding a good way to stain them - dark frames suite many people best but the woods from around here are mostly light. If I could only make them go dark like they do from rubbing with skin. But all over. That would be perfect. Anyone think it could be done?


texts: Does adding mass to a liquid (not water) increase the volume

texts:
The Question sounds stupid but i have a
legit problem

I mixed 1000 mL coconut water and 225 g of agar-agar to make a coconut water [CW] agar. It gave me more than 1000 ml. the medium went beyond the 1000 ml mark. the CW agar was also too soft to use

then i tried mixing 775 mL coconut water and 225 g agar-agar it gave me little below the 1000 mL mark. the CW agar was just right not too soft and not to hard :|

(I did heat after mixing during those two trials but the volume remained the same after cooling to room temp.)

Seems to break rules taught to us.  i though when you add mass to a liquid it won't increase the volume but the density will increase or does this only apply to water?


texts: I am studying astronomy and came across the following term in the astrochemistry course called 'complex organic molecules' or also written as COMs. My question is: What is exactly meant with these molecules? Is it just a molecule with more than one carbon atom?


texts: Why do intramolecular forces weaken due to heat?

texts: In my most recent research into thermoplastics, I was unable to find any information regarding what actually happens to intramolecular forces when heat is applied.


texts: How does de Broglie actually prove Bohr's postulates?

texts:
We know Bohr said that the angular momentum of an electron is an integral multiple of $nh/(2π).$ And in de Broglie's wave equation, he said the circumference of the path of the electron traveling as a way is $n$ times the wavelength, which is equal to $2πr.$

But in Bohr's model $n$ is the principal quantum number, while the $n$ in de Broglie's equation is the number of wavelengths in the one revolution. I don't understand how they are equal.


texts: When is phosphorus a polyatomic molecule?

texts: Phosphorus is listed as a single element in the periodic table; however, I see that it is also a polyatomic molecule as $\ce{P4}$. I am trying to determine the number of atoms of phosphorus in an chemical equation, so I can have a balance equation. So, when would I use the polyatomic version, or the single atomic version if the chemical equation is a word equation, and the subscripts are not listed? For example the word equation is $\ce{P + Cl -> PCl5}$. Is $\ce{P -> P4}$ or just $\ce{P}$? Also, would $\ce{Cl}$ be diatomic too ($\ce{Cl2}$) in this equation?


texts: How is kinetic energy accounted for when describing diatomic bonds with a Morse potential?

texts:
The Morse potential can be used to describe the potential energy of the a diatomic bond:

This curve suggests that the lowest state $v = 0$ is the most stable, since it has the lowest potential energy. However, the energy of a system comprises both potential as well as kinetic energy, and stability should depend on the total energy, not just the potential energy. How does kinetic energy come into play here? Is it being neglected for some reason, or is this description of a diatomic molecule insufficient?


texts: What is the mechanism of formation of alkali metal superoxide?

texts:
I was studying about alkali metals. I can get how oxides and peroxides are formed.
In alkali metal oxides, both of the bonds of the dioxygen molecule first undergoes homolytic cleavage, then the nascent oxygen gets two electrons from two metal atoms.
In alkali metal peroxides, one bond of dioxygen molecule undergoes homolytic cleavage and this results in formation of O-O with one unpaired electron on each oxygen then 2 metal atoms donate their electrons to each of the oxygen.
But how superoxides are formed?


texts:
We currently know that there are atoms with atomic number up to 118 are possible.

Is it possible that atoms with 120 protons are possible, but that atoms with 119 protons aren't possible? Or are there theoretical arguments or maybe heuristic arguments why this can't happen?

I suspect the answer to be yes, because technetium and promethium have no stable forms while the elements surrounding it in the periodic table do have stable forms. A similiar thing might happen here. The more general question: Does there exist $k > l > 118$ such that atoms with $k$ protons are possible, but that atoms with $l$ protons aren't possible?

It is not a duplicate of The last element's atomic number. I wonder whether there could be 'gaps' in the periodic table, not what the last element's atomic number is.


texts: Which atoms in a given amino acid are able to form hydrogen bonds with water?

texts:
Can anyone help me with this question I have tried everything.
I know hydrogen bonding is with $\ce{F}$, $\ce{O}$, or $\ce{N}$, but every time I select those is says it's wrong.


texts:
The cleavage of diborane was presented in a recent lecture, and it was said that the borane could be cleaved unsymmetrically if sterics allowed, or symmetrically if they did not, as shown in the image below:

However, no mechanism for this cleavage was provided, nor can it be found in Housecroft and Sharpe's "Inorganic Chemistry", our course textbook, nor can I find much about it online.

I have postulated such a mechanism:

Is it known how this cleavage occurs, and if it does indeed follow this mechanism? Is my attempt a reasonable proposition?


texts: Disproportionation of plutonium species - Latimer's diagram

texts:
Why (according to provided answers) $\ce{Pu(IV)}$ disproportionates  into adjacent species whilst $\ce{Pu(V)}$ does not in acid aqueous solution.

$$\ce{\underset{(+6)}{Pu}O2^2+ ->[\pu{+1.02 V}] \underset{(+5)}{Pu}O2+ ->[\pu{+1.04 V}]\underset{(+4)}{Pu}^4+ ->[\pu{+1.01V}] \underset{(+3)}{Pu}^3+}$$

I thought it is the other way - the more positive potential of $\pu{+1.04V}$ on the right of $\ce{PuO2+}$ species will drive the disproportionation while in $\ce{Pu^4+}$ the higher value of $\pu{+1.04V}$ to the left renders the species by itself thermodynamically stable.


texts:
First of all, I have zero chemical background, but I seek for an easy explanation about Nano Zinc Oxide.

I was told that the name of "Nano Zinc Oxide" couldn't possibly exist. Instead, it should be coined as "Nano Zinc Chelate", since an Oxide particle is quite big and Nano is so small, relatively. It sounds very contradictory.

I know there is, of course, Nano Zinc Oxide, but I don't understand what he really means and  I feel enthusiastic to understand it.


texts: What chemical reaction could be used to make copper pennies a vibrant red?

texts: I’m an artist working on a piece using pennies to illustrate my drawing and I need my pennies to be red in a certain portion. I’m trying not to use paint and was wondering if there was a way to make them a brownish-red color.


texts:
I'm writing something related to basicity and came across few papers that distinguish thermodynamic and kinetic basicity.

"In particular, the study of hydrogen bonding (H-bonding) within proton sponges has provided rigorous knowledge into the inter-related roles of symmetry, resonance, and aromaticity in H-bonding, as well as a better understanding of kinetic versus thermodynamic basicity and the emergence of a more reﬁned view of the entropic and enthalpic factors contributing to H-bond strength." ( DOI:10.1021/acs.joc.5b01743 )

"There is a tendency, however, that sterically demanding proton sponges with high thermodynamic basicity with strongly protected protonation sites often have a low kinetic basicity." ( DOI:10.1021/ja052647v )

"Thus, this compound class has been the subject of considerable scientific interest challenging chemists from differentfieldstofindsuitablemethodsfortheirsynthesisand handling, evaluate their basicity strength, and understand the principles underlying the thermodynamic and kinetic foundation of their basicity."( DOI:10.1002/anie.201612446)

"The thermodynamic basicity of all newproton pincers was measured by nmr titration experiments with corresponding neutral organic super bases of known pK>25 in CD3CN, while their kinetic basicity was measured by dynamic nmr proton exchange measurements." (Activating Unreactive Substrates: The Role of Secondary Interactions, Edited by Carsten Bolm and F. Ekkehardt Hahn)

So, my questions are:

1) What is the exact distinction between these two terms?

2) Is thermodynamic basicity the one mentioned in common basicity defintions? (arrhenius, lewis, bronsted-lowry)

3) Why are they measured differently?

4) Are they denoted diferrently, do they have different units and is there some general mathematical formula for each that would help me get deeper understanding and distinction between these two terms?

5) Also, how are these two mesaures of basicity related to gas phase proton affinity and intrinsic basicity and pKb?


texts: Why does Calcium have a higher ionization energy than Aluminium?

texts: Given their places on the periodic table I'd assume Aluminium has a higher ionization energy, because it has fewer energy levels, and is on a "righter" row on the periodic table, but in reality it is the opposite. Does anyone here know why?


texts: Dissociation Energy for CO2 per molecule

texts:
I'm trying to calculate the energy required to dissociate a single $\ce{CO2}$ molecule into its respective elements, and I'm given that it takes $ 373.6 \times 10^{3} \, \, \mathrm{\frac{joules}{gram}} $ where  $44.01$ grams is the mass of $6.022 \times 10^{23}$ molecules of $\ce{CO2}$.

By dimensional analysis:

$$\frac{44.01 \ \mathrm{grams}}{6.022 \times 10^{23}~\mathrm{molecules}} = 7.308 \times 10^{-23}\mathrm{\frac{grams}{molecule}}$$

$$\mathrm{\frac{joules}{molecule}} = \mathrm{\frac{joules}{gram} \cdot  \frac{grams}{molecule}} = (373.6 \times 10^{3}) \cdot (7.308 \times 10^{-23}) = 2.7303 \times 10^{-17} \mathrm{\frac{joules}{molecule}}$$

or,

$170.43\,\, \mathrm{eV/molecule}$

Is this derivation and the logical assumptions made herein correct?


texts: An exception to the IUPAC convention for italicisation (typography)

texts:
According to IUPAC, only physical quantities and variables must be italicised.

Section 8 Use of Italic and Roman Fonts for Symbols in Scientific Text of ICTNS Guidelines for Drafting IUPAC Technical Reports and Recommendations states that

  a good general rule is that quantities, or variables, can be given a value, but labels cannot.

So why is it that [X] is not written as [X] when the concentration of species X is a physical quantity?


texts: Entropy and Equilibrium Constant: Chemical Thermodynamics

texts:
For a reaction taking place in a container in equilibrium with its surroundings, the effect of temperature on its equilibrium constant $K$ in terms of change in entropy is described by:
(A) With the increase in temperature, the value of $K$ for exothermic reaction decreases because the entropy change of the system is positive
(B) With the increase in temperature, the value of $K$ for endothermic reaction increases because of an unfavorable change in entropy of the surroundings decreases
(C) With the increase in temperature, the value of $K$ for endothermic reaction increases because the entropy change of the system is negative
(D) With the increase in temperature, the value of $K$ for exothermic reaction decreases because the favorable change in entropy of the surroundings decreases

Now, I am having trouble understanding option (B) (which in fact, is one of the correct options).
Since the process is endothermic and the temperature is rising, the value of $K$ increases, so heat must flow from surroundings to the system to favor the reaction which implies increase in an unfavorable change in entropy of surroundings rather than decrease as given in the option.
Kindly clarify my doubt. Also, any insights (other than the ones already given in the links attached below) into other options are very appreciated.
This question might look Duplicate of the questions already posted here:

relation between equilibrium constant and entropy change

Effect of temperature on equilibrium constant in terms of entropy change

But since this question is not focusing on the same problem, so I hope, it will not be marked as duplicate.


texts: What does a filled, solid circle mean in a chemical structure?

texts:
I'm looking in a textbook at an asphaltene molecule.

The two aromatic rings next to the Nitrogen are shaded. What does that mean? I think the Nitrogen's create delocalized electrons in this configuration, so maybe the shaded circle is the range over which that free radical is delocalized?


texts: How does a Frost diagram reproduce the solutions to the wave equation?

texts:
I came across a Frost diagram for cyclic compounds in my book, and all my book had to offer was that it geometrically reproduces the solutions of the wave equation, and can therefore determine the relative energies of each pi molecular orbital.

How, exactly, does a Frost diagram work? My book was of no use.


texts: Using symmetry and group theory arguments to explain iron(II) in a tetrahedral crystal field

texts:
I am trying to figure out how to explain $1s \rightarrow 3d$ spectroscopic transitions for $\ce{Fe^{2+}}$ in $T_\mathrm{d}$ symmetry. These transitions make up the pre-edge region in K edge X-ray absorption spectroscopy (XAS). My goal is to rely on group theory and symmetry arguments as much as possible. Still, I am interested in the problem from a chemist perspective. I will first discuss what I already know and subsequently formulate my question.
$\ce{Fe^{2+}}$ is a $d^6$ ion with the ground state Russell–Saunders term $^5\!D$. In the event of a $1s \rightarrow 3d$ transition we find the final state configuration to be $1s^13d^7$. To find the corresponding terms we couple the core hole $s^1$ and the $d^7$ terms $$^2S \otimes \{{}^4\!F, {}^4\!P, {}^2\!H, {}^2G, {}^2\!F, {}^2\!P, {}^2\!D(2)\} = {{}^{5,3}F, {}^{5,3}\!P, {}^{1,3}\!H, {}^{1,3}G, {}^{1,3}\!F, {}^{1,3}\!P, {}^{1,3}\!D(2)}$$ From the $^5D$ ground state only the quintet $F$ and quintet $P$ terms can be reached following the quadrupole selection rule $\Delta S = 0$. For the isolated ion (without spin orbit coupling) we thus have two transitions: $^5\!D \rightarrow {}^5\!F$ and $^5\!D \rightarrow {}^5\!P$. So far so good. Now we can include the $T_\mathrm{d}$ crystal field.
In a $T_\mathrm{d}$ crystal field the $5D$ terms splits into $^5\!E_u$ and $^5T_{2u}$. Of these, the $^5\!E_u$ represents the lowest energy $(e_2)^3(t_2)^3$ configuration. Our initial state irreducible representations $\Gamma_i$ thus is $\Gamma_i = {}^5\!E_u$.
$$\Gamma_i = {}^5\!E_u$$
The final state irreducible representations $\Gamma_f$ are obtained by branching the $^5\!P$ and $^5\!F$ terms from $O_3$ to $O_h$:
$$\begin{align}
^5\!F &\rightarrow {}^5\!A_{2u} \oplus {}^5T_{2u} \oplus {}^5T_{1u} \\
^5\!P &\rightarrow {}^5T_{1u} \\
\Gamma_f &= {}^5\!A_{2u} \oplus {}^5T_{2u}\oplus {}^5T_{1u}(F) {}\oplus {}^5T_{1u}(P)
\end{align}$$
The quadrupole transition operator in $T_\mathrm{d}$ symmetry is given by $\Gamma_{\hat{T}} = T_{2u} \oplus E_u$. Now I understand that a transition is possible if the matrix element $\langle f|\hat{T}|i \rangle$ is non zero. To see which final states irreducible representations $\Gamma_f$ are accessible through the transition operator $\hat{T}$ we can take the direct product $\Gamma_i \otimes \Gamma_{\hat{T}}$. This will give:
$${}^5\!E_u \otimes (T_{2u} \oplus E_u) = {}^5\!E_u \otimes T_{2u} \oplus {}^5\!E_u \otimes E_u = {}^5\!A_{1u} \oplus {}^5\!A_{2u} \oplus{} ^5\!E_u \oplus {}^5T_{1u} \oplus {}^5T_{2u}$$
Please correct me if I already made some mistakes. From here I am not so sure how to continue. All the final state irreps $\Gamma_f$ are contained in the direct product $\Gamma_i \otimes \Gamma_f$.

Can i conclude that from the $^5\!E_g$ ground state all of the final state irreps $\Gamma_f$ can and will be reached?
If the only possible final states are $(e_2)^4(t_2)^3$ and $(e_2)^3(t_2)^4$ which $\Gamma_f$ irreps correspond to these configurations?
It is well known that the K pre edge gains intensity for non-centrosymmetric ions with respect to centrosymmetric ions. This is because the $4p$ orbitals can mix with the $d_{xy}$, $d_{xz}$ and $d_{yz}$ orbitals. How does this fit the above storyline?


texts: SMART string for alkyl group excluding alcohols

texts:
I'm quite new to the usage of SMARTS strings. I would like to find all alkyl groups (but no $\ce{CH3})$ in a component, here e.g. cyclohexanol (C1CCC(CC1)O).
My SMARTS string is: [CX4;H0,H1,H2]
However, this matches every carbon. I would like to write my smart string, so that C:3 is not matched, because it is bound to something else than a carbon (here: oxygen). How is this possible with SMARTS?


texts: What does HClO2 aqueous solution decompose to in an open environment?

texts:
I looked up the decompositions of diluted $\ce{HClO2}$ aqueous solution (used in a disinfectant) to know if it is safe to use on some substances, such as metal, wood, leather or skin. However, the chain I found leading to $\ce{HClO4},$ which is a very strong acid.

  $$
\begin{align}
\ce{5 HClO2 &→ 4 ClO2 + HCl + 2 H2O}\\
\ce{4 HClO2 &→ 2 ClO2 + HClO3 + HCl + H2O}\\
\ce{3 HClO2 &→ 2 HClO3 + HCl}\\
\ce{2 HClO2 &→ 2 HOCl + HClO3}\\
\ce{HClO2 &→ HCl + O2}
\end{align}
$$

Then there is

  $$\ce{3HClO3 → 2ClO2 + HClO4 + H2O}$$

(Source: Inorganic Chemistry by Garg and Singh [1], Google book preview)

The $\ce{HClO2}$ solution is diluted (I do not know the exact number, but maybe similar to mild bleach), sprayed to substances' surface, at room or body temperature.

Can the balances in this case lead to $\ce{HClO4}?$

On the other hand, $\ce{HCl}$ recombines to make $\ce{Cl2}$:

  $$
\begin{align}
\ce{HClO2 + 3 HCl &→ 2 Cl2 + 2H2O}\\
\ce{HOCl + HCl &→ Cl2 + H2O}
\end{align}
$$

So, can the remaining $\ce{HCl}$ be concentrated enough to corrode metal or cause harms to skin?

From a consumer's point of view, $\ce{HClO2}$ seems to be a complete disinfectants for all of water, surface (by producing $\ce{HOCl}$), and air (by producing $\ce{ClO2}$). However, the issue left for concerns is the byproduct acids.

Updates: I found a list of patents about producing $\ce{HClO2}$ solutions to be used as disinfectants, which are likely the one I am talking about in this question. The patents claimed that the disinfectants are safe to human, can be used to clean food-processing utilities, and even as food additives. The exact reasons for the claims are not clear to me.

https://patents.google.com/patent/US9516878B2/en
https://patents.google.com/patent/AU2013205834B2/en
https://patents.google.com/patent/EP2999490A2/en
https://patents.google.com/patent/US20160106106A1/en
https://patents.google.com/patent/US20160113282A1/en

References

Garg, R.; Singh, R. Inorganic Chemistry; McGraw-Hill Education: New Delhi, 2015. ISBN 978-1-259-06285-8.


texts: How to determine the pH of a mixture of two weak acids?

texts:
We have two solutions:

Solution 1 is $\ce{HCOOH}$, its concentration is $c_1 = \pu{10^-2 mol/l}$, its volume is $V_1 = \pu{50 ml}$, and its $\mathrm{pH}_1 = 2.9$.
Solution 2 is $\ce{CH3COOH}$, its concentration is $c_2 = \pu{10^-2 mol/l}$, its volume is $V_2 = \pu{50 ml}$, and its $\mathrm{pH}_2 = 3.4$.

How would be the equation and the ICE table, and what is the $\mathrm{pH}$ of the mixture of these two solutions?

I used numbers to differentiate the solutions, and to understand how it works, but for no other reason.

I tried to do $\mathrm{pH}=\frac{1}{2}\left(\mathrm{pH}_1+\mathrm{pH}_2\right)$, but it’s trivial and doesn't work.


texts:
I am simply curious what the theoretical arrangement of metallic hydrogen would be.

I found this article which gives a picture, but I don't understand what the labels mean (e.g. is H5 an isotope, some kind of charge, or just denoting the layer?).

I would like to know:

1) If the image is the correct one.

2) What the labels mean if it is correct.


texts: No sign flipping while figuring out the emf of voltaic cell?

texts:
I learnt that for a voltaic cell, the value for the $E_\text{cell}^\circ$ when the reaction is spontaneous is given by

$$E_\text{cell}^\circ = E_\text{cathode}^\circ - E_\text{anode}^\circ, \label{eqn:1}\tag{1}$$

so that the difference in the right gives us a positive value for $E_\text{cell}^\circ$.

But suppose we are given two half-reactions:

$$
\begin{align}
\ce{Ag+(aq) + e- &→ Ag(s)} &\qquad E^\circ &= \pu{0.80 V} \\
\ce{Sn^2+(aq) + 2 e- &→ Sn(s)} &\qquad E^\circ &= \pu{-0.14 V}
\end{align}
$$

When finding the overall spontaneous reaction, we must flip the second reaction, multiply it by $2$, and then add it with the first to get our desired equation.

But when determining the $E_\text{cell}^\circ$, why don't we negate the minus sign of the second half-reaction and make positive, before we put it in $\eqref{eqn:1}$ to figure out the $E_\text{cell}^\circ$? Shouldn't we do that because we reversed the second equation?

My book tells me to keep the $E_\text{half-cells}^\circ$ as they are written in the tables and simply put them in $\eqref{eqn:1}$. But why?


texts: Dimers and polymers of electron deficient compounds

texts: Why does $\ce{BeH2}$ polymerize into $\ce{(BeH2)_{n}}$ in solid state whereas $\ce{AlCl3}$ dimerises into $\ce{Al2Cl6}$ in the vapour state ?


texts:
Why does the electron-donating inductive effect (+I) of the isotopes of hydrogen decrease in the order $\ce{T} > \ce{D} > \ce{H}$?
(where T is Tritium and D is Deuterium)

Google has nothing to offer. Does it have to do anything with mass, as the order implies?


texts: Why tertiary amines can't show chirality?

texts: Why is a tertiary amine with three different substituents not chiral? Doesn't the lone pair represent a fourth, different substituent?


texts: Absorption Spectrum Using a Spectrophotometer

texts:
After using a spectrophotometer, I have obtained absorbance values. To create an absorption spectrum, should I convert these values to percentage absorbance? (I've seen it in textbooks as such)

If I were to convert absorbance to percentage absorbance, would I simply multiply all values by 100%?


texts: How 'heavy' should an element be, to be a "Heavy Metal"?

texts:
I've come across the term "Heavy metals" innumerable times in articles, mostly pertaining to environmental issues.

Is there a weight range (of sorts) against which an element (metal) is classified as a "Heavy metal"?

Often I see "Heavy metals" refer to Cadmium (Atomic number 48), Mercury (Atomic number 80) and Lead (Atomic number 82), but does this term also apply to metals of intermediate atomic masses [such as Tungsten (Atomic number 50), Gold (Atomic number 79) and Tin (Atomic number 81)]?

I can't seem to find any chemical literature that deals with this, so I suspect that the term "Heavy metal" has no real serious scientific definition.


texts:
It is well known fact that Barium Hydroxide is a base. How does the Brønsted-Lowry concept explain $\ce{Ba(OH)2}$  as a base?

Is it that $\ce{Ba(OH)2}$ first accepts a proton then leaves behind $\ce{H2O}$?


texts: Is it possible to make a drug that liquefies heart plaque to treat heart disease?

texts:
Is it possible to make a drug that liquefies heart plaque to treat heart disease without damaging other parts of the body?  If so, would the liquefied plaque be eliminated as regular fluid is through the kidneys?  I believe that if this is possible, it would definitely be worthwhile to make as it could save many lives!

I heard there are drugs that can dissolve a blood clot.

I also heard of a technique being developed in Israel that dissolves heart plaque with an ultrasonic probe.

It looks like there are some efforts already in this area, but it appears they halt rather than dissolve the plaque:
http://heartdisease.about.com/cs/coronarydisease/a/plaquebuster.htm


texts:
I'm helping to teach some kids about the baking soda/vinegar reaction, and was hoping to point out how the chemical names are just a direct translation of the chemical formula.

However I was surprised to find there is no "2" in the formula for "sodium bicarbonate", $\ce{NaHCO3}$.

Can someone explain where the "bi" comes in?