texts: How does the anti-bonding eg orbital (eg*) affect the bonding of ligands?

texts: In the molecular orbital for octahedral metal-ligand complexes, there is an eg orbital and an eg* orbital. When the d orbitals on the metal split, it will fill up some of the eg* orbitals I believe. However, my question is that won't these orbitals cancel out with the eg orbitals and make fewer bonds? For example, $\ce{Ni^{2+}}$is a $\ce{d^8}$ metal and will split in the presence of ligands and will partially fill the eg* orbitals. The $\ce{Ni^{2+}}$ metal can then form complexes like $\ce{[Ni(H_2O)_6]^{2+}}$ with 6 ligands attached. My question is how would the filling of the eg* orbitals affect the bonding and chemical properties of the compound? Here is the diagram I am referencing to:


texts: Calculating heat capacity of a calorimeter

texts:
I am struggling on this question :

The heat of neutralization of $\ce{NaOH}$ and $\ce{HCl}$ is $-57.1\:\mathrm{kJ}$, calculate the numbers of moles of $\ce{HCl}$ and if $x$ moles of $\ce{HCl}$ were used how many $\:\mathrm{kJ}$ would be given out if one mole results in $57.1 \:\mathrm{kJ}$

I already got the moles as $0.05$ by doing $n=\frac{v}{1000}  c$ where I had $50\:\mathrm{mL}$ of $2\:\mathrm{M}$ $\ce{HCl}$


texts: The third ortho effect is, according to Wikipedia, the phenomenon where in a ring with a meta and an ortho-para director both meta to each other has the incoming nucleophile go ortho to the meta director rather than para. Why is this? I would think that the ortho-to-meta position would be destabilized due to a stronger inductive effect.


texts: Regioselectivity in iodolactonisation of γ,δ-unsaturated carboxylic acid

texts:
In the last step of the iodolactonisation of 3,3-dimethylpent-4-enoic acid,[1,2] why does the carboxylate attack the iodonium to form a 5-membered ring, when a more stable 6-membered ring is possible? Both of the sites seem to be equally favorable sterically. I can't come up with a reason favoring the formation of the 5-membered ring.

References

Takano, S.; Sato, N.; Akiyama, M.; Ogasawara, K. A Synthesis of trans- and cis-Caronaldehydes. Heterocycles 1985, 23 (11), 2859–2872. DOI: 10.3987/R-1985-11-2859.
Ding, Y.; Jiang, X. A Novel Highly Stereoselective Synthesis of the A-Ring of Taxol Via Two Aldol Reactions. J. Chem. Soc., Chem. Commun. 1995, 1693 DOI: 10.1039/C39950001693.


texts: Why is dimethyloxonium cation stronger acid than hydronium?

texts:
$\ce{(CH_3)_2O^+ H}$ has $\rm pK_a \; -3.8$ while $\ce{H_3O^+}$ has $\rm pK_a \; 1.74\;.$ So, the former is stronger acid than latter hydronium ion.

But why is it so?

Is it due to the $\rm +I$-effect of $\ce{-(CH_3)}$? But it would rather decrease the attraction of $\ce O$ on the electron pair of $\ce H$ and that would make it indifferent to release $\ce {H^+}$ isn't it?

What is actually going that makes $\ce{(CH_3)_2O^+ H}$ stronger acid than $\ce{H_3O^+}$ ?


texts: Create metallic nanstructure on aluminum or copper film

texts:
I want to etch Al/Cu film (0.05 mm thick) to create nanopatterns on to the surface of the film. The etched surface should be metallic. The idea is to develop a simple tribolectric nanogenerator with good current output. For that I need to increase the surface area by nanostructuring as well as maintain the conductivity. I read that Al treated with NaOH is used to create nanopatterns but the patterns created are oxides of Al and Na in which is conductivity is lost. I particularly want to avoid any wet treatment because I am considering sheet sizes of 5 cm x 5 cm.
At the end I want that nanopatterning to be done with minimum resources available.


texts: Identify the strongest base without knowing the pKa

texts:
I have some doubts about this question:
Which of the following aniline derivatives is the strongest base?
(I think is 3, because the molecule has 2 atoms of O and N, but I'm not sure.)


texts: On the exact definitions of Frenkel and Schottky defects

texts:
The wiki page on vacancy defects says;

It is also known as a Schottky defect, although in ionic crystals the concepts are not identical.

As far as I'm aware, they're the same. Furthermore, the wiki page for Schottky defects contains the term 'vacancies' while describing the phenomenon, which is linked back to the page for vacancy defects. That seems contradictory.
Are they the same? And is the same true for Frenkel and interstitial defects? Or are the named ones subsets?


texts:
Somewhere along the line of researching why the $\ce{Cl-C-H}$ bond angle in methyl chloride is less than what is predicted ($\pu{109.5^\circ}$), I ran into a book which said that the electron withdrawing effects of the chlorine atom gave the $\ce{C-Cl}$ bond more "p-character".

What does this mean? Is he simply using this term to describe the elongated nature of the bond - i.e. s-orbitals are spherical and p-orbitals not spherical but rather elongated (at least as depicted by cartoon drawings in textbooks)?

Is the author saying that the electron-withdrawing effects of chlorine cause the electrons to spend more time further away from the nucleus; hence the "p-character"? I understand that in a spherical shell, electrons are basically equidistant from the nucleus. But in an elongated, "p-character" shell, electrons can go further away from the nucleus.


texts: Why we have mass of adsorbent in Freundlich equation?

texts:
In Freundlich equation why we have $m$ the mass of adsorbent. I mean it is surface chemistry and on the surface of adsorbent the adsorption takes place so why we have mass of adsorbent in that equation.

Let us understand my problem by an example.

In my book it is given that when we add charcoal to a solution of acetic acid in water then the acidity of the solution is decreased because charcoal has adsorbed some amount of acid.

Now let us have two beakers with acetic acid in water with same concentration and let us have $m$ gram of charcoal. In the first beaker you add the charcoal in shape of a cube and in the second beaker you add the charcoal in the powdered form.

Since the surface area of charcoal available for adsorption in second case is more and so there will be more adsorption and this means the final concentration of the second beaker will be less as compared to the first beaker.

Please tell me why we have mass of adsorbent in Freundlich equation rather than surface area? In the example above we were having same mass of adsorbent but the extend of adsorption was different and this is the reason why I think that mass of adsorbent in useless. If there is some use of mass of adsorbent in the Freundlich equation then please tell me.

EDIT

In the above example of acetic acid we have considered two cases in one we adding charcoal in the shape of cube and in the second one we are adding charcoal in powdered form.

In both the situation adsorbate and adsorbent are same and are at same temperature so the value of $K$ and $n$ is same for both situations. Also we have taken concentration to be same in both the situation so $c$ is also same for both the situations. Mass of the adsorbate that is mass of the acetic acid is also same in both the situations.

Also take the same mass of charcoal. Now according to the Freundlich equation the concentration of acetic acid in water after adsorption has to be same in both the situations because in both the case we have same value of $K,n,c,x,m$. But this is not true since we know that more the surface area more will be the adsorption therefore in the second case when we have added the charcoal in the powdered form then it will adsorb more acetic acid as compared to the first case where we have added the charcoal in the shape of a cube.

Sir I don't have equipments to perform this experiment but I have some logic.

Statement 1 Freundlich equation is true.

Statement 2 More the surface area more will be the adsorption.

Now here I can say without any doubt that one of the above statement is clearly wrong.

I request the readers to please see the example and please try to understand  what I mean to say.


texts: What should I do about working in a laboratory that I believe is unsafe?

texts: I currently work in a lab that frequently gives me anxiety about safety. We work with toxic fumes daily. The sliding sashes on the fume hoods are held up by cinder blocks. There is a large crack in the glass of one of the hoods. We have an abundance of work so everyone is always rushing through SOPs. I see people pull beakers out while toxic gases are still fuming. We've never even had a safety drill on what to do if there is a chemical spill. We had an audit a few months ago and somehow passed? How should I address this situation? Thank you.


texts:
In 2,2-dichloropropane the Cl–C–Cl angle (108.3°) is less than the C–C–C angle (113.0°).

In Me$_2$TiCl$_2$, in contrast, the Cl–Ti–Cl angle (116.7°) is larger than the C–Ti–C angle (106.2°).

How is this discrepancy explained?


texts: Charge-transfer absorption complex - solvent sensitivity

texts:
This is a quote from Anslyn's Physical Organic Chemistry:

  [...] One way to think of these systems is that the ground state is a weak,
  intermolecular complex, (D • A). Often such molecules are polar and /
  or quite polarizable, facilitating complex formation. Because one
  partner is intrinsically a good electron donor (low ionization
  potential) and the other is a good acceptor (high electron affinity),
  the excited state will have a large contribution from states such as
  (D+• A-) that involve electron transfer, a configuration not possible
  for either isolated molecule. This preferentially stabilizes the
  excited state, leading to a lower energy (longer wavelength)
  absorption.  Because of this highly polar character, charge-transfer
  absorptions are extremely sensitive to solvent polarity, moving to
  longer wavelengths as the solvent polarity increases.

Earlier I read about Franck-Condon principle but I lack QM-mathematical background behind, so that's why this principle still leave me at unease, and hence my question. How is it possible that absorption wavelength is so sensitive to solvent polarity, when significant charge develops not until the complex is excited? I mean how the excited state of the molecule "knows" there is solvent ready to solvate it, since according to Frank-Condon principle solvent rearrangement is much slower than absorption.


texts:
I was given a molecule that I had to identify the NMR of. The molecule is 2-methylpent-1-ene (shown below):

The correct NMR spectra for this molecule is:

My question is, why is this the right spectra for this molecule. Particularly, how and why did the single peak come up? As far as I know, the only two single peaks are the two that are downfield (aka closest to the $\ce{sp2}$ hybridized carbon).


texts: Predicting pH of an acidic salt of an weak acid and weak base

texts:
Suppose we want to calculate pH of an $\ce{NH4HCO3}$ solution of known concentration.
Now, $\ce{NH4+}$ will be hydrolised to give $\ce{H+}$ ions.
Some $\ce{HCO3-}$ ions will be converted to (i) $\ce{H2CO3}$ and $\ce{OH-}$
and some will give (ii) $\ce{H+}$ and $\ce{CO3^2-}$

\begin{align}
\ce{HCO3- + H2O &<=> H2CO3 + OH− }& 1/K_\mathrm{a1}\\
\ce{HCO3- + H2O &<=> CO3^2- + H3O+ }& K_\mathrm{a2}\\
\ce{NH4+ + H2O &<=> NH3 (aq) + H3O+ }& 1/K_\mathrm{b}\\
\end{align}

I am not sure how to take account of both $\ce{H3O+}$ and $\ce{OH-}$ in the calculation of pH.
Will the third equilibium costant be $1/K_\mathrm{b}$?


texts: Simple Ethyl Acetate synthesis in absence of catalyst

texts:
To smoothen 3D printed PLA parts I need ethyl acetate. This is a pretty cheap solvent to synthesize but still to expensive to buy, so I would like to make it myself.

I have seen that ethanol and acetic acid are combined in a Fischer esterification with sulfuric acid as catalyst, then the solution gets distilled afterwards to yield ethyl acetate. I don't have sulfuric acid but I have:

Ethanol 95% (with impurities to make it non consumable)
Acetic acid 8%

Also, I don't really have to distillate the solution since the other chemicals don't harm the PLA. Will simply mixing these two solutions produce a little bit of ethyl acetate? And how can I maximize the yield?


texts: Is it possible to determine the age of a building by just looking at its window?

texts: I've recently come across the fact that glass is an amorphous solid and is known as a pseudo solid or a super cooled liquid. Our teacher told us that buildings that if we were to closely observe the glass in the window panes, we would find that it's thicker at the bottom. I'm now wondering if we can calculate the difference between the width of the top and bottom of the window, would it be possible to determine an approximate age of a building?


texts: What happens if you put a piece of copper into a solution containing Al3+ ions?

texts: This is a question in my studies, and I am a little bit confused! I would think it happens nothing because copper is below aluminium in the reactivity series, right?


texts:
Does anyone know how I can render chemical structures of small organic molecules to look like the below images?

I have been looking around, and I cannot seem to find an answer. The closest lead I had was this link saying you can "copy" your ChemDraw then "paste" into Chem3D. I looked through Chem3D's manual and found no such rendering style as the pictures linked above.

I know Chimera can do Simple Line Drawing but it seems to render small molecules only within the plane. I have seen plenty of examples of proteins, but I am trying to find something for small organic molecules.

I have also found references to the style named after the artist David Goodsell. I have seen this style referred as a non-photorealistic rendering referenced in this sci-hub link, page 11, figure 9.  Again, I have seen this shell/toon shading for large biomolecules, but not for small molecules.

Any help would be appreciated. I linked to a few sources above hoping it might help someone else trying to find similar rendering styles.


texts: Azathioprine CIF data file rendering problem in Accelrys

texts:
I have been working on a CIF data file based on experimental data [1] (free full text isn't available, but the page 2 with the experiment details can be found in the free preview provided by Springer).

Unfortunately, I don't know an awful lot about crystallography parameters (although I have been consulting the CIF core dictionary). The CIF file I linked to was created using EnCIFer & VESTA (I mostly used VESTA to get a handle for the text formatting of CIF files). The non-coordinate data mentioned in this paper includes:

\begin{array}{ll}
\hline
Z & 4 \\
\text{Formula} & \ce{C9H7N7O2S} \\
M_r & 277.3 \\
\text{Coordinate system} & \text{monoclinic} \\
\beta & 105.99^\circ \\
a & \pu{4.488(2) Å} \\
b & \pu{31.886(4) Å} \\
c & \pu{8.067(2) Å} \\
V & \pu{1149.5 Å^3} \\
D_m & \pu{1.59 mg mm^{-3}}\\
D_c & \pu{1.60 mg mm^{-3}} \\
\lambda & \pu{0.7107 Å} \\
\text{Space group} & P2_1/c \\
\text{Crystal dimensions} & 0.7\times 0.1 \times 0.7\, \pu{mm} \\
\hline
\end{array}

The problem is that Accelrys DS Visualizer so far renders my CIF file as:

Notice how some of the hydrogen atoms are disconnected from the main chunk of the azathioprine molecule.

Acharya, K. R. Proc. Indian Acad. Sci. (Chem. Sci.) 1984, 93 (2), 183–187 DOI: 10.1007/BF02842141.


texts: Major product of radical fluorination vs bromination

texts: I understand what structure is formed by using $\ce{Br2}$ to brominate this alkane, and I know that $\ce{F2}$ will be less selective in its abstraction of hydrogen. However, how can I know where $\ce{F2}$ will primarily react with this alkane? I just know that $\ce{F2}$ will react more readily and be less selective.


texts: How would you find the expected molecular orbital energy diagram for compounds such as NO?

texts: How would you find the expected molecular orbital energy diagram for $\ce{NO}$? Would it be the expected one for $\ce{O2}$? Or the one for $\ce{N2}$? Also, would the ionization energy be bigger than that of$\ce{NO+}$?


texts: How is it possible to distinguish antimony from lead?

texts: I just bought some (pure) antimony stones from a local store. However, I've heard that some stores deceive their customers by selling lead instead of antimony. I was wondering if there is any simple test that I can perform at home to make sure these stones are antimony and not lead. Since I don't know much about chemistry I thought of asking here...


texts: Equilibrium of more than two inter reacting species

texts:
We know that equilibrium in a chemical system is attained when forward and backward reaction rates are equal. What if the reaction mixtures involve more than one reaction?

For example, consider three inter-reacting species A, B and C. The rate constants for the forward and backward reactions of $\ce{A -> B}$ are $k_1$ and $k'_1$, that of $\ce{B -> C}$ are $k_2$ and $k'_2$ and that of $\ce{C -> A}$ are $k_3$ and $k'_3$. What is the relation between the six rate constants so that the system remains in equilibrium? Assume first order kinetics for all the reactions. Thanks in advance.


texts: The meaning of the sulfite anion attached to the benzene ring

texts:
I needed to work with PEDOT:PSS solution, so I also looked up it's chemical composition and the wikipedia page threw up this pic.

I need to understand how the sulfite anion is connected to the benzene ring in the structure on the right. I have studied it in chemistry in my school days but I have not really used it afterwards, hence I have forgotten. Your explanations will be appreciated.


texts:
Why is the ideal gas law usable in most gas problems?

For example, in a problem like this: "Suppose you have $1.00\: \mathrm{mol}$ of a gas at $0\:^\circ \mathrm{C}$, occupying a container which is $500\: \mathrm{mL}$ in size. What is the pressure of this gas in $\mathrm{atm}$?"

The ideal gas law is was applied to solve that problem and the answer was $44.8\: \mathrm{atm}$. But isn't the ideal gas law only applicable to gases which are in high temperatures and low pressure? Because the kinetic energy overcomes the intermolecular bonds and the molar volume is negligible, etc etc.

But the conditions for this "gas" are low temperature and consecutively high pressure which is basically a stamp for real gases so why isn't the real gas law applied to this problem instead?


texts: Is the structure of a crystalized protein the native one?

texts: When one finds the 3D structure of a protein by crystalizing it and then making a X-ray experiment, how does one know that the geometrical configuration of the crystal is the same (or even close) to the structure the protein adopt in aqueous solution?


texts: Corrosion of a galvanic couple made with silver and gold

texts:
If a bangle is made out of gold and silver, connected with each-other would there be corrosion happening?
If so, can it be explained using the galvanic series?

Also do those metals undergo oxidation under normal conditions?


texts: Calculating energy level from wavelength

texts:
The transition of an electron from a higher level to a lower level results in the emission of a photon of wavelength $350.0\ \mathrm{nm}$. If the energy of the higher level is $-3.24\times10^{-19}\ \mathrm J$, calculate the energy of the lower level.

By using $E = h\nu$

I find $E = 5.679\times10^{-28}\ \mathrm J$

How do I use this value to solve the qus?


texts: How much NaOH required to change the pH of a weak acid solution by 2

texts:
If I have a $\pu{20mL}$ $\pu{0.1M}$ solution of sodium dihydrogenphosphate, how much $\pu{0.1M}$ $\ce{NaOH}$ do I need to add to raise the $pH$ by 2.

Here's what I've done so far. I'm doubt it's right and I get stuck with respect to the change in volume.

Edit: I realize that this wrong as sodium dihydrogenphosphate is polyprotic.

I found using the $K_a$ that a $\pu{0.1M}$ solution will lead to a $[\ce{H+}]= 3.47\times 10^{-5}$

Since $-log(3.47\times 10^{-5}) = pH = 4.46$, the pH of the final solution is $4.46 + 2 = 6.46$.

The change in $[\ce{H+}]$ is $3.47\times10^{-5} - 10^{-6.46} = 3.44\times10^{-6}$, so there must be a concentration of $3.44\times10^{-6}M$ $\ce{OH-}$ added to the solution.

Since my solution is $0.02L$, $0.02 \times 3.44\times10^{-6} = 7\times10^{-8}$ moles of $\ce{OH-}$.

The ratio of $\ce{OH-}$ to $\ce{NaOH}$ is $1:1$, so:

$\pu{0.1M}$ $\ce{NaOH} = 7\times\dfrac{10^-8}{x}$, $x = 7\times10^{-7} mL$ of $\pu{0.1M}$ $\ce{NaOH}$ added

I know this is a VERY small amount of $\ce{NaOH}$ but is there a way to account for the fact that this change in volume will affect the $pH$ of the solution?


texts: Mechanism of Friedel-Crafts acylation with succinic anhydride

texts: Here is my proposed mechanism, something tells me that the intramolecular deprotonation happens after, and that this is not concerted. Is my mechanism correct?


texts: Can every liquid pure substance be compressed to solid?

texts:
Apart form the fact that liquid are often misleadingly considered incompressible,
fact that I recently find out to be true only as an approximation in specific circumstances.
I was curious to know if it's a property of all elements that they can be turned from liquid to solid by applying pressure.
In fact by looking at the different phase diagrams and at the general one, seems an intrinsic property of the elements the capacity of becoming solid under some pressure.
A description of what happens at the atomic level, addressing the reasons for the phenomena would be appreciated too.


texts: How to measure the speed in a catalized reaction?

texts:
What is cheaper?

Set up a constant time of reaction and measure the concentration of the products or;
Set up a constant quantity of reactants and, with an indicator, measure the time until the reaction stops.

If you know another protocol, Can you explain it, please?


texts: Crusty white armpit stain that can't be removed by washing

texts:
Some of my t-shirts (the ones that are 100% cotton) started developing this strange armpit stain:

it makes the fabric feel brittle and crusty around it;
it can't be washed off with water and detergent;
it can't be scrapped off easily.

Now here's some information about the environment my clothes live in:

our water is moderately hard (60-120 ppm);
I use a deodorant that has the following ingredients:

I sweat a lot and our climate is quite dry.

I was thinking I'm dealing with a boring calcium carbonate deposit, but I don't really want to start drowning all my stained shirts in vinegar without first knowing what I'm dealing with. What do you guys think it is and how would you get rid of it?


texts: Can someone explain 3‐(propan‐2‐yl)cyclohex‐1‐ene forming a carbocation?

texts:
Can someone explain this one, especially the formation of the secondary carbocation (in the solution)?

Solution:

After the electrophilic attack by $\ce{H+}$ on the π bond, I had expected the carbocation formation on the other side (the left end of the π bond) because of more hyperconjugation thus ruling out the chance of its rearrangement to the tertiary site. I've seen this happen in other questions too.


texts: What is an algorithm for making a net neutral molecule from a set of guessed positive charges?

texts:
Given a set of partial charges for the atoms in a molecule, which are educated guesses but do not add up to zero, we would like to zero them in an intelligent way.

For example, if the net charge is negative and we see a +0.1 atom bonded to a -0.9 atom, we should probably shift the -0.9 towards zero to make that section of the molecule more neutral.

There is also chemical information which can be used, eg, keep oxygen atoms positive and don't let the charge on hydrogen be greater than 1.0.

Is there a name for this class of problem? What algorithms can be applied?


texts:
I know this question has been asked previously but I cannot find a satisfactory explanation as to why is it so difficult for $\ce{H4O^2+}$ to exist. There are explanations that it is so because of $+2$ charge, but if only that was the reason then existence of species like $\ce{SO4^2-}$ should not have been possible.

So, what is exactly the reason that makes $\ce{H4O^2+}$ so unstable?


texts:
Assuming that electrons behave as both waves and particles, and that waves(like in double slit experiment) can interfere with themselves:

Do electrons actually move in any direction, or do they just 'teleport'(similar to how when making a Quantum Leap, they instantaneously appear at a different shell, rather than actually move continuously).
Do electrons 'subtract' with other electrons for the probability function of an electron being present in that location. i.e. if there is a covalent bond, will the electrons interfere with the other probably function aside from repelling it?.
Do electrons only have positive probabilities. Is it more like how gravity never repels, only attracts, or more similar to how waves of light have peaks and troughs. Do electrons ever cancel out with others? If so, how?


texts:
I've obtained a simple air quality analyzer which measures several items, formaldehyde concentration among them. While I cannot vouch for its correctness, I found the values measured during the last few days worth asking about.

Wherever I go, the analyzer measures higher than ideal levels of formaldehyde. From reading a bunch of papers, I concluded that the "safe" value is around 0.1 mg/m3. However, I can only measure so little on fresh air, outside, where it is around 0.04 - 0.08 mg/m3.

Indoor locations include:

At my folks' place which has not been recently renovated or painted, has no new furniture and the levels are around 0.180-0.280 mg/m3.
In my apartment which has some newer furniture and has been painted a couple of years ago, levels are from 0.250-0.450 mg/m3. I do open windows often and try to vent but the levels easily spike over 0.1 mg/m3.
At my office, which is not renovated, has no new furniture and has a lot of air, always above 0.150 mg/m3.

There is no smoking at any of these locations.

From what I read, this values are in line with furniture factories. I'm a little bit confused and worried, because I'm not sure what to make of this. Are there ways to reduce the concentration of indoor formaldehyde? Might it make sense to get a second analyzer to corroborate the results?

Background: I'm an electrical engineer and not too much into advanced chemistry or health & safety. I've spent some time looking through papers and publications, but a lot of them are about WHS and not easily understandable by me, quoting different methodologies or abbreviations I can hardly pick up.


texts: Value of the frequency factor in the Arrhenius equation

texts:
Is the value of 'A' necessarily the same for two different reactions taking place at the same temperature?

It's actually a part of another question which is if the rate constant k1 of a reaction is found to be double that of rate constant k2 of another reaction the relationship between corresponding activation energies of the two reactions at the same temperature (e1 and e2) can be represented as e1__e2


texts: Balancing Redox reaction : with 2 species being oxidized

texts:
I have a redox reaction I found from a chemistry book from the 1970's.
Two chemical species are oxidized, the Chromium and Iodine.

$\ce{CrI3 + KOH + Cl2 -> K2CrO4 + KIO4 +KCl + H2O}$

Hope someone can help on how to balance this.


texts: Is there a relationship between pH indicator colors and the visible light spectrum?

texts:
When I examined the colors showed on a pH paper which is red for acids and violet for bases, greenish yellow for neutral and other ranges in between, I noticed that the sequence is exactly same to that of visible light spectrum that is violet, indigo, blue, green, yellow, orange, and red.
Is there a connection between the two, and if yes what it is?


texts: Do tetrachloroaluminate salts hydrolyse?

texts: Tetrafluoroborate salts, such as lithium tetrafluoroborate, are reasonably stable in aqueous solutions. Does the same hold for sodium tetrachloroaluminate as well or does it end up as $$\ce{NaAlCl4 + 4H2O -> NaAl(OH)4 + 4HCl}?$$


texts: Most efficient way to purify household vinegar: distillation or freezing?

texts: I am aware that there are better ways to purify acetic acid out of a water-acid mixture than these, but which one out of distillation (using heat) and fractional freezing (using cold) would gain a higher concentration of acetic acid?


texts: Why does Fluorine have a high affinity for Calcium?

texts: I keep hearing from several websites and videos that Fluorine seems to like bonding to Calcium specifically; can someone please tell me why? I can't seem to find a clear response on the internet. Fluorine has a high affinity to Calcium, more than other elements. Why is that?


texts: What explains the case hardening color effect?

texts:
Year 11 chemistry student here.
I'm curious about how the case hardening effect works on metals.
I know that when the electrons gain an energy 'level' or lose an energy 'level' they emit light at differing frequencies.
So why does the outside of metal, after being heated, stay those pretty rainbow colors after they cool down?


texts: Finding equilibrium constant from solubility product constant

texts:
Given
  $$\ce{CuI(s) <=> Cu+(aq) + I-(aq)}\, ;\qquad K_\mathrm{sp} = 1.2 \cdot 10^{-12}$$
  write a reasonable chemical reaction that describes the decomposition of $\ce{CuI2}$ in aqueous solution, and show that this is a spontaneous reaction under standard conditions.

The answer found the Gibbs free energy change of the precipitation reaction (backward reaction of the one shown above) using the formula $\Delta G = -RT\ln{K_\mathrm{eq}}$ and substituted the value $1/K_\mathrm{sp}$ for $K_\mathrm{eq}$.

I do not understand why the inverse of the solubility constant can be used as the equilibrium constant of the backwards reaction.

Is it a rule that the equilibrium constant of any backwards reaction is equal to the inverse of the equilibrium constant of the forwards reaction?


texts: Is the application of Le Chatelier's principle wrong in this case?

texts:
In the reaction:
$$\ce{N2(g) + 3H2(g) <=> 2NH3(g)}$$
Suppose the system has 3 moles of $\ce{N2}$, 1 mole of $\ce{H2}$ and 1 mole of $\ce{NH3}$ at equilibrium. $Q_\chi=K_\chi=8.33$ and $Q_p=K_p$.

Now I add 5 moles of $\ce{N2}$ in the container by keeping (i) pressure and (ii) volume constant (temperature constant in both).

According to Le Chatelier's principle:

If pressure is constant: equilibrium shifts to backward direction.
If volume is constant: equilibrium shifts to forward direction.

But if I look at the equilibrium in terms of mole fraction, $Q_\chi$ will be the same in both the cases and hence equilibrium should shift in the same direction i.e. in backward direction.

Why do they predict different equilibrium states?

[$K_\chi$ is equilibrium constant in terms of mole fraction, $K_p$ is equilibrium constant in terms of partial pressures].


texts: What is the purpose of trimming the bottom corners of TLC plates?

texts: During my chemistry lab course, I was told by my instructor to make 2 small cuts on the bottom corners of the TLC (Thin-Layer Chromatography) plate. Does this make the solvent rise uniformly on the plate? Is this a standard practice in labs? I could not find any information online. In this question the OP has made the cuts as well, but this does not seem to make the solvent rise uniformly.


texts: Is there a pH at which all proteins are negatively charged? How can it be determined?

texts: I know that depending on the amino-acid-composition of the peptide the distance to the isoelectric point determines the charge. Is there a universal point at which all proteins are definitely negatively charged?


texts: The reaction of Alkyl Halides with sodium nitrite in DMF

texts:
How does the reaction of Alkyl Halides with sodium nitrite in DMF proceed?

I was aware of the reaction of alkyl halides with aqueous sodium nitrite which results in the formation of an alkyl nitrite but I came across the following reaction and was confused of how that would work?
$$\ce{R-X + NaNO2 ->[DMF] R-NO2}$$
DMF being the solvent here, I'm pretty sure it's safe to assume that it will be following $\mathrm{S_N2}$ path here but since I have never seen this reaction before, I'd appreciate if someone could enlighten me.
Also, looking at the reaction, I thought maybe DMF makes the sodium nitrate covalent somehow? (I know this is baseless but that's all I could think) which looks quite confusing.

I came across a post very similar to this but I think that didn't answer what's being asked. So I was hoping if someone could explain the mechanism of this (including if its $\mathrm{S_N1}$ or $\mathrm{S_N2}$)?


texts: Most energy-dense commercial battery available

texts:
What's the most energy-dense and currently commercially available chemical battery technology? Would it be the Lithium-Ion Polymer or has it been surpassed already?

There's is a chemical non-rechargeable battery which is more energy-dense than LiPo, even if it's less power-dense?

I'm trying to have a general sense of the current state-of-the-art technology, as the Wikipedia articles and tables seems to be very dated.

Edit: I meant "dense" as in respect to mass. I believe that "specific energy" would be the right terminology.


texts: When does copper leach to water? Conflicting faqs

texts:
I have heard conflicting reports:

Copper leaches to water only when the water is high in acid or the Copper is corroded.
Copper leaches to water any time, especially when it is new copper or the water is hot.

Which one would be correct?


texts: Why does density decrease across the period 4 and 5 transition metals?

texts: I know that density decreases across period 4 because the last two elements are liquids and gases which means that their densities are less but why are the densities increasing and then decreasing within the transition metals themselves?


texts: Inversion of Configuration - Opening of Epoxide

texts:
This doesn't look like a traditional inversion of configuration:

At first I dismissed the textbook author as making a typo. But then I realized that this "typo" was repeated throughout the solutions manual.

So I tried drawing a Sawhorse projection of the textbook's answer and my answer, and I found that both are equivalent.

So would my answer also be acceptable? In my answer I change the methyl from a wedge to dashes and the hydrogen from dashes to wedge and I place the SH group appropriately.


texts:
I'm a 7th grader, and this is what is printed in my Chemistry textbook:

An Acid is a chemical compound that is sour in taste and is soluble in water.
A base is a chemical compound that is bitter in taste.
A salt is a compound that is form alongside water when an Acid and a Base reacts.

Come on. That can't be what Acids and Bases are! What is an Acid, a Base and a Salt?


texts:
Why does the long length of the fractionating column in fractional distillation enable more effective separation of two liquids in a mixture?

(basically what's the purpose of the fractionating column being long in relation to the effectiveness of the fractional distillation process)


texts: When two containers at different T and P are kept together, will pressure become same or temperature?

texts:
Two containers, kept at different temperatures are connected through a stopcock and two different ideal gases at different pressures are filled inside them. Initially the stopcock is closed. When the stopcock is opened, will the pressures become same or will thermal equilibrium be established first? Why?

Here's an extract from an online source about thermal equilibrium-"As we have seen in the zeroth law of thermodynamics, when two objects are placed in contact heat (energy) is transferred from one to the other until they reach the same temperature (are in thermal equilibrium). When the objects are at the same temperature there is no heat transfer."

We are taught in class that after the stopcock is opened, gaseous molecules travel from container at higher pressure to the container with lower pressure. There wasn't any discussion on thermal equilibrium. If the temperature of two gases kept at different temperatures don't become equal, isn't that a violation of zeroth law?

When the stopcock is opened, the gas molecules at different temperatures do come in contact. So, why thermal equilibrium is not established and instead there is a greater driving force to make pressure in both the containers same?


texts: Why using smaller portions are better for extractions

texts: Why is using one smaller portion more efficient than using one large portion for extraction. No math answer please thank you


texts: Why is absorbance in UV-VIS spectrometer negative even after calibration?

texts: I was collecting data to plot a calibration curve using pure beta-carotene sample. Prepared 5 different concentrations of beta-carotene dissolved in methanol. Pure methanol was used as blank. However, data collected for all 5 concentrations observed was negative (between -0.005 and -0.010) at 610nm ( orange region along the spectrum). Please advice.


texts: Can an ethyl ester of L-proline be synthesised from the amino acid and ethyl alcohol in toluene with azeotropic distillation of water?

texts:
I was told that the ethyl ester of L-proline may not be synthesized from L-proline and ethyl alcohol in refluxing toluene, with an acid catalyst such as p-toluensulfonic acid for example, because toluene and ethanol and in this case water as well form an azeotrope. Is this true?

I do not have a supply of pure thionyl chloride, and that's why I am trying to use this route. I appreciate if anyone may answer this question.


texts:
Nitrogen triiodide, on slightest physical contact, explodes to evolve dense purple fumes of iodine. Why does this phenomenon occur?

video link - https://www.youtube.com/watch?v=2KlAf936E90


texts: Any examples of liquids volatile at room temp but non-flammable?

texts: I'm thinking of something similar to the liquid used in the classic dipping birds. Temperature differential in two "bulbs" at each end of a tube should cause vapor to expand and push liquid to the top, shifting the weight and tipping it. The closer to room temperature the boiling point is, the better. Thanks.


texts: Are primary, secondary, and tertiary amines considered functional group or chain isomers?

texts:
Consider $\ce{C3H7NH2}$.  Can one make $3$ different isomers with this molecular formula? My question is that are they functional group isomers or chain isomers?

I have been told that they are functional group isomers but I intuitively think that they are chain isomers.


texts: What is the underlying chemistry behind the triboelectric effect?

texts: I remember briefly studying the triboelectric effect in Physics but as I now approach the domain of Chemistry, I'd like to know what processes are involved (at the molecular level) when the the triboelectric effect comes into play. What variables (if any) would have have to be considered when conducting an analysis of the triboelectric effect?


texts:
I remember back in my high school, when we started electrolysis, I became quite interested in it. I decided to do a home experiment on electrolysis of water. I grabbed my graphite pencils, a glass of water made of steel, two wires and some water. I wrapped the wire on my graphite nibs(on one end) and immersed the other end in water. I connected the wires to 240V AC supply(that was the supply which powers our home.)

Observations:

Initially, bubbles formed on both of the electrodes(I think they must be a hydrogen/oxygen mixture since the cathode and anode switches in between due to ac)

The glass of water became very hot with the passage of time(which was due to resistance heating i suppose)

The interesting part came when I added a few grams of table salt to water. Within seconds, the graphite rods turned red and there were fumes of gas(most probably it was steam cause the fumes were white.) There might have been sparks in the plug as well, but I don't remember for sure. I immediately pulled the plug out before it got any worse.

I didnt try anything of that sort again as i knew i could have done worse than that. But it doesnt cause any harm in knowing what actually happened when I added salt.

Why did the graphite turned glowing red?

What was the composition of those fumes?

What more could have gone worse?


texts: How to predict the effusion/diffusion for a mixture of gases?

texts:
Suppose a a container contains a gaseous mixture of methane and hydrogen. The mixture effuses out through a hole in the container. Now hydrogen is lighter gas so it must effuse faster and all of hydrogen should come out of the flask earlier than methane (before all methane effuses out) and a stage should come when there is only methane left in the container.
Is this how it happens?


texts: Going from La to Ce, why is the extra electron added into the 4f orbital?

texts:
So, I am studying electronic configuration but the elements of the series of the lanthanides confused me. The electronic configuration of $\ce{La}$ is $\mathrm{6s^2\,5d^1}$ and that of cerium is $\mathrm{6s^2\,5d^1\,4f^1}$.

So, why does the extra electron that was added make the $\mathrm{5d}$ orbital have a higher energy?


texts: Do all metal salts in aqueous solution contain metal aquo complexes?

texts: I know that nickel nitrate in aqueous solution contains the metal aquo complex ion $\ce{[Ni(H2O)6]^2+}$. But do all metal salts in aqueous solution contain such complex ions? If not, on what factors does the formation of metal aquo complex ions depend? Is the metal required to be a transition metal?


texts: Where can I find (citable) FTIR spectra of CuCl and CuCl2?

texts: I can't seem to find any published/citable infrared (FTIR) spectra in the 4000-400 cm-1 range of CuCl and CuCl2. Does anyone know of a source available, either free or paid?


texts: How to use C1V1=C2V2 How do the units work?

texts:
I am trying to do a dilution where I know I have 0.749 g/ mL and I want to use this concentration to calculate the grams of aspirin in each 100 mL solution. I am specifically worried about the units. I want grams out. Is it valid to do the following?
One:
$$C1V1=C2V2$$
$$(0.749 g)(1 mL)=(C2 g)(100mL)$$
$$C2=0.00749 g$$

or must I do this?
Two:
$$C1V1=C2V2$$
$$(0.749 g/mL)(1 mL)=(C2 g/mL)(100mL)$$
$$C2=0.00749 g/mL$$

The difference being the final units. g vs. g/mL


texts: Why doesn't open-chain glucose react with water readily in aqueous solution?

texts:
Though the exact number given varies from 0.02% to 3%, it's well agreed that glucose spends a very small percentage of its time in aqueous solution as a linear aldehyde. Glucose's overwhelming preference as a cyclic pyranose is commonly explained by the cyclization being intramolecular; while the aldehyde group in its linear form can react with other molecules like protein and lipids during rare encounters, it far more readily reacts with an alcohol group that is always around by virtue of being on the same molecule.

My problem with that explanation is that there is indeed another molecule that is always around in aqueous solution: water. All sources I could find said that the common instability of hemiacetals and geminal diols are both explained by oxygen repulsion. Therefore, I would expect there to be a glucose-geminal diol concentration comparable to the cyclic hemiacetal concentration in aqueous solution, yet I cannot find any mention of a glucose-geminal diol, as if it didn't exist. What am I missing?


texts: How fast do electrons move around the nucleus?

texts: Electrons, as we all know, are incredibly small. Smaller things do tend to move faster, right? So exactly how fast considering how small they are? Also, does the electonegativity between two atoms alter the speed of the electron?


texts: What is the dipole moment direction in the nitrosonium ion?

texts:
In the recent question about the molecular orbitals of $\ce{NO^{$x$}};\ x\in\{-1,0,+1\}$ the follow-up title question arose:

  Just a random side-question: What’s the dipole moment’s negative and positive sides in $\ce{NO+}$?

At the time I was unable to answer that question sufficiently, therefore I share the addendum Q&A style. The question further deconstruct the molecular orbital components to the dipole moment.


texts: Why must the leaving group in E1cb be poor?

texts: Typically the leaving group for E1cb is poor (like -OH or -OR) but why must this be the case? The substrate appears in the rate equation so surely a good leaving group would be beneficial?


texts: How to calculate planar density of a face /plane of crystal with cation and anions?

texts:
Planar density is given by numer of atoms in plane /plane area  .
Suppose I want to calculate
planar density of 100, 101 and 111 planes of Nacl. Radius of Na+ and Cl- ions is 0.086 nm and 0.126 nm.Na+ are present at octahedral voids and cl- at FCC but the problem which I am facing is that I cannot add simply the number of atoms in given face/plane  for calulation of numer of atoms(zeff) as sizes of cation and anion  will be diffrent .What should I do??


texts: Where do I go to get details on setting up different instruments?

texts: Say I want to set up a system to preform cyclic voltammetry. How do I know what instruments to get/ electrochemical cells/ etc? Is there a resource for other setups as well, like EIS?


texts:
From Costanzo's Physiology book in Acid-Base Physiology chapter, this titration curve of a weak acid ($\ce{HA}$), in the context of discussing buffers is provided:

What confused me is that in this diagram, the $\mathrm{pH}$ is on the $x$-axis rather than the $y$-axis. Also, why does the peek of the curve has ($\ce{HA}$) only and the trough has ($\ce{A-}$) only?


texts: Difference in the acidity of ethanoic and methanoic acid

texts:
Peter Sykes attributes the difference in their acidity to differential solvation.

From what I understand, there is not much difference in how well the ions are solvated, since the Delta H is comparable, however, the change in entropy is much greater for ethanoic acid but I don't understand why?


texts:
In the TV show "Breaking Bad", Walter White frequently gets rid of people who get in his way by submerging them in a plastic container full of hydrofluoric acid. This, at least in the TV show, completely dissolves the body leaving nothing but a red sludge behind at the end.

Is it actually possible to dispose of a body with hydrofluoric acid?

If hydrofluoric acid wouldn't work, are there any acids corrosive enough to achieve the stated effect from the show?


texts:
Does resonance always stabilize a molecule or can resonance effects destabilize molecules?

The only example I can think of in which resonance (more accurately, conjugation) destabilizes molecules is in the cases of anti-aromatic compounds. Is this a valid example, and are there any more such examples?


texts: Which platonic solids have been built as carbon skeletons?

texts:
There are 5 platonic solids: the tetrahedron, the octahedron, the cube, the dodecahedron and the icosahedron.

How many of these have been realised as carbon skeletons by chemical synthesis?


texts: Determining the lowest rank non-vanishing multipole moment

texts: I have been told that the multipole moments of rank 0,1,2,3,...n have respectively 1,3,5,7,...2n+1 components which transform like the spherical harmonics of rank 0,1,2,3,...n. How do I use the character tables to determine the lowest rank non-vanishing multipole moment for the following molecules: $\ce{H2O, BF3, CF4, CO2, SF6}$?


texts: energy efficiency, transformation from chemical to thermal energy, for district heating plants

texts:
If I have a system in which I introduce $\mathrm{100~e.u.F}$ (energy units) derived from chemical energy (i.e. fuel) and generate thermal energy to heat water what are e.u. absorbed by water? I.e. the efficiency of the transformation?

Basically I would like to know the "average/general" efficiency of energy transformation for a district heating plant. Considered that the only energy input is fuel and the only energy output is heat (no electricity)?

What are the energy loss?


texts: How to predict the outcome of a crossed Cannizzaro reaction?

texts:
My question is, how do we predict the products of a cross-Cannizzaro disproportionation in presence of a concentrated base? i.e, How to judge which of the aldehydes (both don't have any alpha hydrogen) is reduced and which one is oxidized?

If we are asked

$$\ce{CH3-O-C6H4-CHO   + HCHO ->[OH^- (conc)] ?}$$

Case: if we see acc to RDS, which is hydride transfer, we must see which compound is better hydride donor. Then it will be $\ce{CH3-O-C6H4-CHO}$. This will get oxidized, and $\ce{HCHO}$ reduced.

Case: if we see which is a better nucleophilic substrate, $\ce{HCHO}$ will get oxidised, and $\ce{CH3-O-C6H4-CHO}$, reduced.

Now my problem is, which of the above cases is correct? i.e, do we see which one of the substrates is better $\ce{H-}$ donor, or which one of them is a better nucleophilic substrate?

Please advise which case is correct, and how to approach such problems.


texts: Can 0-Carborane be stored at room temperature?

texts:
I am a physics post-doc at Oak Ridge National Lab (with a bit more training in chem than the average physicist). I ordered a small sample of o-Carborane from Sigma-Aldrich to test for doping liquid scintillators for neutron capture. Everything I have read about carborane says that it is crazy stable and should be fine at room temperature as long as it is kept dry.

However Sigma-Aldrich says to store refrigerated at 2-8C. I called them and found out that this is because they sell it without an expiration date "We cannot guarantee product quality and performance if the product is not stored at the recommended temperature." However, I know that they ship it at ambient temperatures. I am currently trying to get them to send me confirmation that it is not a safety concern to just keep it in a dessicator (which we have), merely a quality concern (and a mostly imaginary one at that).

I am posting this because I am not certain of all the places I could look to find information that would support this conclusion and I need the support to go to the safety people and show we do not need to buy a chemical fridge to store this stuff. I found found SDSs that simply say cool dry place, I have seen safety data sheets that say refrigerate, I even saw one that said to keep it below -18C.

Can anyone point me towards a good source for definitively saying "It is safe to store o-carborane at room temperature in a desiccator" (or similar)?


texts:
So we are doing calculations with the first law of thermodynamics:
$$U = q + w$$

And we have been studying $\mathrm dU(T,V)$.
So it is true that for some equations of state other than the ideal gas equation, $\mathrm dU(T)$ only, so therefore it follows that $U= C_V(T_2-T_1)$. So I am wondering is it even possible that $C_V$ is used for non-ideal gasses? And would it also be equal to $\frac 32R$?
And if $C_V$ can be used, why?
(Also is this true for $C_p$?)


texts: Does the Dieckmann Reaction proceed via the conjugated enolate of the product?

texts:
In the following mechanism of the Dieckmann Condensation, the product has been formed in the fourth step, but still the reaction proceeds and $ \ce{RO^{-}}$deprotonates the product. Then $\ce{H^{+}}$ rejoins to form the same product. Won't this result in extra expenditure of energy? Also, if the reaction proceeds through this mechanism, shouldn't there be an infinite loop?

Can anyone explain why is there an extra step?


texts:
I was asked in one question that which of all given molecules have a permanent dipole moment?

And $\ce{XeF6}$ was given as a correct answer quoting that it is a distorted octahedral, and hence the lone pair results in the molecule having a dipole moment. But since we know that the lone pair goes at each face of the octahedral one by one, the net effect should cancel out. Hence, is it correct to say that the molecule has a PERMANENT dipole?

I am having similar doubt in the case of the very fundamental ammonia example. Since it undergoes inversion do we say that it has a permanent dipole?

Basically what is the meaning of a permanent dipole? I understand how it is different from induced dipole and instantaneous dipole, but these examples feel like instantaneous dipole examples to me.


texts: Are bulkier molecules more likely to react?

texts: I have heard a theory from someone and just wanted to confirm if its true or not. Is it true that more bulkier an organic compound is, more likely it is to react? So does this mean that higher the molecular weight of an organic compound, more will be the probability of it to react?


texts: Why can acidification of solution lead to selective precipitation of ions such as Fe2+ and Zn2+?

texts:
Given $K_\textrm{sp}(\ce{ZnS})= \pu{2.5E-22}$ and $K_\textrm{sp}(\ce{FeS})= \pu{3.7E-19}$, why would $\ce{Fe^{2+}}$ ions remain in solution but not $\ce{Zn^{2+}}$ with acidification of the solution?
I have little understanding of this, so I don't have a great attempt at the solution.


texts: What is meaning of unit (mg-Pt/cm^2) in relation to fuel cells?

texts:
I do not understand what the meaning is of the unit

mg-$\ce{Pt}$/cm$^2$

which I have come across in reading about the theory of fuel cells.

In simple terms, what does this unit mean?


texts:
My textbook, as well as practically every online source I have looked into, says that when you collect gas over water, the pressure of the trapped gas plus the vapor pressure of water at that given temperature is equal to the outside atmospheric pressure, or $P_g + P_v = P_a$.

However, this doesn't make much sense to me, as the weight of the column of water below the gas is being ignored (or at least that's how it seems to me). Shouldn't the external/atmospheric pressure equal the total pressure of the trapped gas(es) above the water PLUS the pressure contributed by the weight of the water below the trapped gas (just like how the force exerted by the weight of the water column is considered in a barometer or manometer)?

Thanks in advance for helping me clear this confusion up.


texts: Examples of evolving networks in chemistry

texts:
I'm a master student working on networks analysis in general. A network is something that has nodes and there are links between the nodes. Nodes and links could have attributes. An evolving network is one that changes overtime (new nodes and links are added..etc). An example of that is Facebook. Nodes are users and links represent the friendship relationship. Users have attributes (gender, age ..etc). A Facebook network as you know is an example of a social network.

The issue is that so many people studied traditional evolving networks like social networks, the web, or transportation networks. Currently I'm looking for novel examples of evolving networks to study them. So I thought there might be some examples in chemistry that could represent some kind of an evolving network.

So my question: Can you give me examples in chemistry for evolving networks?


texts: Formula for rate constant for the first order reaction

texts:
My lecturer mentioned that the formula for the rate constant $k$ for the first order reaction is
$$k = \frac{2.0303}{t_{1/2}}\,\log\frac{[\ce{A}]_0}{[\ce{A}]_{t_{1/2}} - [\ce{A}]_0},\tag{1}$$
where $t_{1/2}$ is the half-life; $[\ce{A}]_0$ is the initial concentration; $[\ce{A}]_{t_{1/2}}$ is the concentration at half-life.
In which what I know recently is that the rate constant for the first order reaction is
$$
\begin{align}
&  & \ln\frac{[\ce{A}]_t}{[\ce{A}]_0} &= -kt \tag{2}\\
&\implies & [\ce{A}]_t &= [\ce{A}]_0\,\mathrm e^{-kt}\tag{3}
\end{align}
$$
I ask my teacher, but he said I should go and do more research, but I couldn't find it.


texts: Are there any examples of activating meta directors?

texts:
I have heard about activating ortho-para directors. For example: methoxy group, hydroxy group, alkyl group, et cetera.

I have heard about deactivating ortho-para directors. For example: halogen substituents

I have heard about deactivating meta directors. For example: nitro, trifluromethyl group, carboxylic acid group, et cetera.

So, naturally, I have embarked on a quest to find Activating Meta directors.

I have found one potential candidate, which is dimethylphenylborane:

Boron possesses a vacant $\mathrm{p}_z$ orbital, which can interact with the $\pi$-cloud of the benzene ring.

Considering the fact that boron is treated as a metalloid, it will definitely be less electronegative than carbon, so the dimethylborane group should offer a good +I effect, which could possibly outweigh the -M effects.

Can anyone shed some light on this issue? Are there any other examples of activating meta directors?


texts: Zinc sulfide is used in road signs because when light from cars hit the road signs, it glows. What actually is the reason for the glowing of road signs (actually glowing of $\ce{ZnS}$)?


texts: Is the 'n' in Delta G = -nFE, ever negative?

texts: Is it possible for $n$ in $\Delta G=-nFE$ to ever be negative? Trying to figure out where I went wrong on some thing and want to rule that out.


texts:
How can I accomplish the above conversion?

My thoughts:

One way of introducing the double bond, would be using the appropriate Grignard Reagent after oxidation of t-butanol (somehow)
I think that initial conversion to carbonyl compound is necessary - only then can we follow up with nucleophilic addition.

P.S. The question was in the organometallics section of my assignment, possibly hinting that reagents apart from the above species may be used. However, won't it be great if we could design a mechanism using only the starting species and commonly available reagents?


texts:
I have a sample of an iodine solution that has been dyed brown to mask the amount of iodine within.

I have added activated carbon to 100 mL of the sample and mixed for 3 hours to remove the iodine from the solution but now I'm having trouble recovering the iodine back into solution.


texts: Dissolving plastic resin without damaging aluminium surface

texts:
I have an aluminium surface covered with some plastic, which I intend to dissolve in order to clean the surface. On the note for the plastic I have applied, it says that it contains the following:

2-butanone Naphtha
Hexane
Toluene
Resins

What solvent would you recommend to dissolve this plastic, without damaging the aluminium underneath? Could I simply reapply the solvents that were used initially (naphta, hexane, toluene and the ketone)? Regular petrol should contain up to 15% of the toluene, would it be safe to clean it with petrol?


texts:
I would like to know what is valence molecular connectivity index of 3rd order cluster. Please provide an example?

Thanks for your help.


texts:
A full bottle of jewelry cleaning (links product and material safety data sheet below) broke in my car and went unnoticed for a few days.  Now the car has a sulfur-like smell whenever I go into the car.  It dissipates within a few minutes, but then returns very quickly once I leave the car.

The primary chemical components are alcohol ethoxylates, and can decompose into carbon monoxide, carbon dioxide nitrogen Oxides, sulfur oxides and other toxic gases.

I have cleaned the area and had the carpet (rear driver) shampooed from a car detailer, but still the smell remains.

What chemical compound can I use to neutralize the smell permanently (enter equilibrium)?

Product Link (Amazon)
Product Link (Manufacturer)
Material data safety sheet


texts: Is there an equivalent unit cell that can describe a bcc unit cell where all points are the same element?

texts: Similar to how an NaCl-structure can be described as just a primitive cubic structure if all the lattice points were the same element or ion. I'm asking if there any such alternative for the CsCl-structure.


texts: Compound with a bright green emission when electrically excited

texts:
I rolled back the edit because I really am looking for the following:

I am looking for an element or compound that would have a bright green emission when electrically excited and is a gas at between 1 torr and 4 torr. If such a compound could be nontoxic, that would be beneficial.

The pressure range is important.

I'm familiar with the emissions spectra of all the noble gases, but none of them work for me. I want to find such a compound to use in a Geissler tube, which will be excited with about 50kVac at 300 to 500kHz. I am capable of pulling a vacuum down to 0.2 torr, and I normally work between 1 torr and 4 torr.

I know of a Xenon/nitrogen mix that produces the desired color, but it's too fussy for me to achieve, and Xenon is too expensive for this purpose.

Relatedly, I was wondering why the Xenon/nitrogen mixture emits a green light. Neither Xenon or Nitrogen has much green at the appropriate pressure, but somehow the combination, within a narrow range of Nitrogen partial pressure, produces a bright green.  What causes this color when the two compounds are mixed together, and how can I predict the color of a given mixture of gases at a given pressure?

I know of the bohr model and balmer series etc, but I don't understand how to apply that to compounds or mixtures of compounds. Is there some other way to predict the spectra produced by mixtures of gases?

It's not easy gettin' green!  (Apologies to Kermit)


texts: Sticking coefficents for dissociative adsorption

texts:
I am trying to simulate the decomposition of Hydrogen Peroxide ($\ce{H2O2}$) on $\ce{Pt}$ using Chemkin Pro. I am using a two step global reaction model for the reaction which is as follows-
$$\ce{H2O2_{(g)} + Pt_{(s)} -> PtO_{(s)} + H2O_{(g)}}$$
(I have taken $\ce{Pt_{(s)}}$ to be a empty site and put all NASA polynomials for Thermo data as zero for it)
$$\ce{Pt_{(s)} -> Pt_{(s)} + 0.5 O2_{(g)}}$$
I am using sticking coefficient for the 1st step, but I am unable to understand how Chemkin handles dissociative adsorption. There is no mention of this in the manual.
So my main doubt is, does the rate of reaction of the 1st step calculated from sticking coefficients will be same for production of $\ce{H2O}$ and $\ce{PtO_{(s)}}$, as in the amount of $\ce{O}$ that will stick on the $\ce{Pt_{(s)}}$, will be same as amount of $\ce{H2O_{(g)}}$ produced?
Any help will be appreciated.


texts: Bond order of H2O and NH3 using group theory to construct MOs

texts:
The bond order of H2O is 2, and that of NH3 is 3, which makes sense, when considering the number of bonds they have.

However, if using basic group theory, you get the MO diagrams as presented in this paper:

http://www.scielo.br/pdf/qn/v35n7/v35n7a32.pdf

Upon examination, we see that in the case of H2O, there are two orbitals that are strongly bonding, one weakly bonding orbital, and one non-bonding orbital. If we then tried to apply the bonding order equation to this MO diagram, would we not end up with a bond order of 3 - despite the a1 orbital being only weakly bonding, its occupation still stabilizes the molecule relative to its constituent atoms. Is it the case that the concept of bonding order breaks down using these kinds of MO diagrams?

A further example is given using the NH3 MO diagram. Here, they calculate the bond order as 3, ignoring the fact that the NH3 a1 orbital is weakly bonding. If we were to in theory calculate the MO diagram for NH3 in a trigonal planar geometry (same as for BH3), we would also get the bond order as 3. Of course, the occupied a1 orbital is weakly bonding in the trigonal pyrimidal NH3 geometry, leading to a preference over the trigonal planar geometry, but why is this not reflected in the bond order?


texts: Why does the non-volatile solute go into the liquid part of the the solution when a solution containing non-volative solute is freezed?

texts: My teacher gave the following diagram in the class notes. He said that when a solution containing a non-volative solute (for e.g.  a solution of $\ce{NaCl}$ in water) is freezed, then there will be some depression in freezing point and some part of the solution will freeze and some part won't freeze due to the presence of the non-volatile solute. My teacher said that the non-volatile solute which is trapped in the solid solvent will gradually move into the solution which has not freezed and make it more and more concentrated until finally we get a pure solid solvent on one side and a highly concentrated solution containing the non-volatile solute on the other side. But why does the non-volatile solute go into the part of the solution which has not freezed? I mean it is trapped in the solid solvent, right? So, why does it go into the liquid part? In the diagram $\ce{NaCl}$ is moving from frozen water to liquid water and eventually all of the $\ce{NaCl}$ from the frozen water will go into the liquid part. But why does this happen? What is the reason behind this? Please explain. I am so confused. Please help (In the diagram the arrows show the movement of the $\ce{NaCl}$).


texts:
For comparing stability of carbanion, we use the fact that "negative charge is stable on more electronegative atom." So, The stability order is, {electronegative order: $\mathrm{sp \gt sp^2 \gt  sp^3}$} and therefore, $\ce{HC#C^- \gt H2C=C^-H \gt CH3-C^-H2}$.
My doubt is that, we generally say, carbanion is stable when there is less electron density on $\ce{C^-}$.
In $\ce{HC#C^-}$, $\ce{C}$ is $\mathrm{sp}$ hybridized that means it is more electronegative, so it will pull electrons more as compared to other two. So, electron density order will be reverse of above order. And, $\ce{HC#C^-}$ will be least stable.
By, my thought, answer is completely opposite.
Please help me to get out of this doubt and please correct me if I said something wrong.


texts: Chondroitin Sulfate (greater volume in solution than in crystal form)

texts:
I've read in a textbook on biophysics that chondroitin sulfate occupies a greater volume in a solution than in crystalline form. Why is that?

Is it because of hydrogen bonds in solution that the volume is larger?


texts: Chemical accuracy is $\pu{2E-2 eV}$ but room temperature $\pu{20 ^\circ C}$ is $\pu{2.5E-2 eV}$, so why is it not necessary to take into account thermal effects in DFT? I understood (maybe wrongly) that chemical accuracy is the precision we want on electronic energies for one atom or one molecule.


texts: Can we combine two reactions and then calculate the equilibrium concentrations?

texts:
At a certain temperature, $\ce{N2O5}$ dissociates as:
  \begin{align}
\ce{N2O5 (g) &<=> N2O3 (g) + O2 (g)} & K_1 &= 4.5
\end{align}
  At the same time, $\ce{N2O3}$ also dissociates as:
  \begin{align}
\ce{N2O3 (g) &<=> N2O (g) + O2 (g)}  & K_2 &= \mathrm{?}
\end{align}

  When 4 moles of $\ce{N2O5}$ are heated in a flask of $\pu{1 L}$ volume, it has been observed that the concentration of $\ce{O2}$ is $\pu{4.5 M}$ at
  equilibrium. What are the equilibrium concentrations of the other products?

The combined reaction:

$$\ce{ N2O5(g) <=> N2O(g)  + 2O2(g)}$$
$$K_\text{combined} = K_1 \times K_2 = 4.5 K_2$$

There are 4 moles of $\ce{N2O5}$ initially. If $x$ moles of $\ce{N2O5}$ dissociate to give $x$ moles of $\ce{N2O}$ and $2x$  moles of $\ce{O2}$, then plugging in the values in the $K_c$ expression for this reaction we get
$$4.5 K_2 = \frac{4x^3}{4-x},$$
where
$$x = \frac{4.5}{2 \pu{mol}}.$$

Solving for $K_2$, I get $K_2=\frac{81}{14}$, which is incorrect.

Is it allowed to first combine the reactions and then use the combined reaction?


texts: How many kilograms of graphite are consumed while producing 4 kg of Al through Hall-Heroult process?

texts:
How many kilograms of graphite are consumed while producing 4 kg of $\ce{Al}$ through Hall-Heroult process?

This looks like a simple stoichiometry problem:
$$\ce{4Al^3+ + 12e- -> 4Al} \; \; \; \; \; \text{(at cathode)} \\
\ce{3C ->[O2] 3CO2 + 12e^-} \; \; \; \; \; \text{(at anode)}$$
For every $4$ moles of $\ce{Al}$ consumed, $3$ moles of $C$ are consumed. The mass of graphite consumed is thus:
$$M = \frac{4000}{27} \times \frac{3}{4} \times 12 = \pu{1.33 kg}$$
However, my textbook mentions the answer to be $\pu{2 kg}$, along with the following explanation:

for every kilogram of $\ce{Al}$ produced, approximately $\pu{0.5 kg}$ of graphite is consumed.

Why is this so? Could anyone provide a valid reference?


texts: How to analysis the amount of reactive oxygen atom in specific molecules

texts:
From a Phd dissertation here, I read about the material follows:

  "Odd oxygen is a measure of oxidative capacity of the atmosphere. It contains species with an oxygen atom avaliable to serve as an oxidizing agent."

The author summed the species as $O_3$, $O$, $O^1D$, $NO_2$ and $2\ NO_3$, etc as the whole odd oxygen.
The species which has more than one reactive oxygen atoms are counted multiple times to represent he total number of reactive oxygen atoms.

How to analysis the amout of reactive oxygen atom of certain species like  $NO_2$ and $2\ NO_3$


texts: Will sodium thiosulfate react with nitrate and/or nitrite ions

texts: I am doing nitrate and nitrite quantification in raw water and treated water using a colorimetric method. The manufacturer of the instrument states that water with chloride will interfere with the test result. I was thinking to inactivate the chloride in the water with sodium thiosulfate. However, I am not sure how is sodium thiosulfate react with the nitrate and nitrite in my sample. Thanks in advanced for any guidance provided! Cheers!


texts:
I thought it is just me, but when I searched it on Google, it revealed that there are many people who experience this:
Why is it that whenever I taste my own blood, I always think it tastes like rust?  I have never eaten or tasted rust, so how can I relate something to it?


texts: Why does a molecule with a Thiol group form Hydrogen bonds?

texts:
I'm doing the GRE Biology practice test, and question #1 asks:

The answer is E. I understand why II and IV are polar, but why is $\ce{R-S-H}$ polar? R is a side chain to the sulfur, sulfur's valence shell is full, and sulfur is highly electronegative. But without knowing what $\ce{R}$ is, how do we know the molecule's total polarity?


texts: What does ingredients being "biologically active" mean?

texts:
From Wikipedia

  Cosmeceuticals refers to the combination of cosmetics and
  pharmaceuticals. Cosmeceuticals are cosmetic products with
  biologically active ingredients purporting to have medical or
  drug-like benefits.

I was wondering what  ingredients being "biologically active" means?

In cosmetics that are not cosmeceuticals, are their ingredients not "biologically active"?


texts: Why there is an Upper Explosive concentration Limit?

texts:
If we have a mixture of combustible gas (let's say it's methane) and air, what is the physical explanation for having a upper concentration limit?
I found this document:
Lower and upper explosive limits

For example, methane has 5% and 15%.
Let's say we have a 30% concentration of methane... There is still enough oxygen, so that some of the methane could burn.
There won't be any combustion at all, or there is some combustion, but no explosion?


texts: Why do experiments not verify the law of mass action?

texts:
I read the answer to Rate Law vs Law of Mass Action and it's written in the answer:

    In the rate law, the rate equation consists of actual factors that changes with change in experimental conditions. These may or may not
    be equal to stoichiometric factors. These are generally responsible
    for determining the order of reaction.

  Both the laws are correct because both have a wide area of
  application. Rate law is although quite experimental in nature and is
  generally considered to be more appropriate.

Why do reactions not obey the law of mass action? And if that's the case, then how does it even have any applications? Shouldn't all problems be solved using the rate law only?


texts: Relationship between basicity and electron withdrawing ability

texts:
Quote from a textbook (Organic chemistry, Fourth Edition by Paula Yurkanis Bruice):

  "A weaker base is a more electronegative  base; that is, it is better able to accommodate its negative  charge. Thus, weaker bases are better at withdrawing electrons inductively from the carbonyl carbon; electron withdrawal increases the carbonyl carbon’s susceptibility to nucleophilic attack."

Iodide is a weaker base than fluoride. So according to the textbook quote, iodide has a greater electron withdrawing ability than fluoride.

But the iodine atom is less electronegative than fluorine atom. How is it that the iodide ion is more electron withdrawing?


texts: Why there exist no void with co-ordination number 5

texts:
Here

      oh = octahedral
      td = tetrahedral
      CN = co-ordination number

My problem is that, that why it is not possible to have a void with CN = 5 ?

My reasoning is:

According to the definition of CN i.e. the number of nearest neighbors of a particle (here a void because we are talking about it).

In the following figure if we treat silver sphere as the void then we say that it is a td void.

But if we place a sphere over this td void then we generate a void whose distance from center of void to the center of all the 5 spheres is equal. And so making the CN = 5

So kindly help me in understanding that why a void with CN = 5 not possible.


texts: I was wondering if it was possible to create Silane from Methane using the process of siliconization to replace the Carbon with Silicon. For example Silicon Carbide is produced by replacing C-C bonds with a Si-C bond.


texts: Are all 'dextrorotatory' sugars in biology actually 'd' or '+' in chirality?

texts:
When papers or articles say that all proteinogenic amino acids are 'levorotatory' or 'L', they often make a point of saying that only half of them are truly, optically levorotatory.  All of them (except glycine) are called 'L' because of their 'opposing' configuration to glyceraldehyde, the original molecule deemed to be dextrorotatory...
Well, all sugars used by living things are supposedly 'R', or so I keep reading....
Are they similar in configuration to glyceraldehyde, or actually levorotatory to light?


texts: How does hot air remove guests from cyclodextrin?

texts: Cyclodextrin, as I know, has a hydrophobic cavity. Therefore, it would absorb hydrophobic organic compounds. But the organic compound can also be removed with hot air since the interaction between the organic compound and the cavity is an induced dipole attraction. How much heat would be enough to break the attraction and how would it break the attraction?


texts: Why do batteries drain so quickly if they are forced to draw more current than they normally do?

texts:
When a battery is pushed to use twice the current it normally does, it lasts for less than half as long before dying...
In fact, batteries often come with a 'C' rating that gives you an idea of how long they might last when run at a high current level...
What is going on inside the battery when this occurs?  What is the chemistry, so to speak?


texts:
Which bond is stronger?  N=O or C=N?
I tried comparing it using electronegativity difference. But, I don't know if that is the correct method. Can anyone explain it?


texts: why is potassium the most free element in most of plants

texts:
Potassium is known to be the most freely available mobile element.
I am wondering why that is the case?  Is the answer hidden in its atomic structure or its monovalent cationic existance?


texts: Where did amino acids get their one-letter codes?

texts:
Some amino acids have a one-letter code that's just the first letter of the name of the amino acid. This makes sense and obviously, since there is more than one amino acid that begins with the same letter, other letters had to be used.

But why were these other letters chosen? For instance, is there a reason 'W' specifically was chosen for tryptophan (other than the fact that 'T' was taken)?


texts: Software for computations of rovibrational states' energies and corresponding spectroscopic constants in diatomic molecules

texts:
I need to compute rovibrational energy levels and also the spectroscopic constants, especially $\omega_e$ to compare my results with other papers.

So far I've tried LEVEL16, which seems very promising, but, unfortunately, it seems, that it provides just some of the constants, as described in How to obtain spectroscopic constants Omega_e, Alpha_e, B_e, D_e and D_0 from centrifugal constants?.

Also I've tried Psi4 and Molcas Vibrot, but none of them is able to fit my potential energy curves precisely enough and contrary to LEVEL16 they don't provide parameters to modify interpolation behavior.

Finally I've tried Duo, but I found out, that it isn't able to compute rovibrational energy levels and constants from point-wise computed function as described in this issue.

Do you know any other software, which could be used to compute both the rovibrational energy levels AND the spectroscopic constants including $\omega_e, \alpha_e, B_e, D_e$ and $D_0$?


texts:
I have the following two spectra (IR and 1H-NMR) see below.

The chemical formula is: C16H16O2

Thus DBE = 9

My approach:

From the IR, I can see that there's no broad peak around 2500-3300, thus I can rule out any carboxylic acids and alcohols.

Then I'll look at the sharp peak at 1734 which makes me suspect an aldehyde.

From the H-NMR I see the following:

This is where I run into some issues.

I see peak a and c as -CH2- groups next to another R-CH2-, but in two different chemical environments.

And I suspect that peak d might be caused by two benzene rings (2x5H=10H) in a symmetric molecule, like; Ar-R-Ar but I can't stitch these informations together to something useful.

I hope that someone can help me out.


texts:
An isotopic variant of the molecule SF$_6$ is S$^{19}$F$_4^{18}$F$_2$, with the two $^{18}$F nuclei oriented axially, so that the $^{18}$F-S-$^{18}$F angle is 180°and the four $^{19}$F nuclei form a square in a plane perpendicular to the $^{18}$F-S-$^{18}$F axis. All of the bond lengths are equal.  In the figure, the regions surrounding the $^{18}$F nuclei are shown in blue, and the regions around the $^{19}$F nuclei are shown in green.Two of the moments of inertia of S$^{19}$F$_4^{18}$F$_2$ are identical, and the third is slightly larger: I$_A$= I$_B$ = $2.9942 ×10^{-45}$ kg m$^2$ and I$_C$= $3.0749×10^{-45}$ kg m$^2$. Wikipedia describes SF$_6$ as an “extremely potent greenhouse gas.”

What is the symmetry number of S$^{19}$F$_4^{18}$F$_2$?

I have considered it and think there is one 4-fold axis, and two 2 fold axes, but still unsure if that is right


texts: Why do (did) they make trans fat instead of using saturated fat?

texts:
When making chocolate unsaturated fat is used for a good melting point (and perhaps health reasons.)

To make chocolate edible it has to be a bit more solid, so other fats were required. Therefore they use trans fats, which are unsaturated fats made saturated in cis or trans form.

Why do they do that instead of just mix it with normal saturated fat? Why use trans fats?


texts: First, I would like to say that I understand the basic idea of disassociation and solubility. However, as I study intermolecular forces I feel like this basic Idea is being challenged. My understanding from basic chemistry is that ionic bonds are much stronger than covalent bonds, due to the actual exchange of electrons and the formation of cations and anions, causing an attractive force between the opposite charges to "hold" the compound together. When explaining solubility with IMF theory, however, I fail to understand how the IM forces present in water--dipole-dipole, H-bonds, and dispersion--are able to overcome that attraction between the cation and anion present in the ionic bond; because, I was under the impression that actual bonds are always stronger than IMF bonds. So, for instance, does it not infer that if, say, Sodium Chloride is placed into water, and the attraction of the h-bonds in water cause the NaCl to essentially break apart into ions, that the inherent attractions between cations and anions in an ionic compound are weaker than the attraction force of the h-bond water molecule?


texts: Anomalous oxidation states of Transition Metals

texts:
I have noted down the available positive oxidation states of the first
  row of transition elements (on the Periodic Table) from the respective Wikipedia articles of
  the elements.

  $\ce{Sc} - 3, 2,1$

  $\ce{Ti} - 4, 3, 2, 1 $

  $\ce{V} - 5, 4, 3, 2, 1$

  $\ce{Cr} - 6, 5, 4, 3, 2, 1$

  $\ce{Mn} - 7, 6, 5, 4, 3, 2, 1$

  $\ce{Fe} - 6,5,4,3,2,1 $

  $\ce{Co} - 5,4,3,2,1 $

  $\ce{Ni}-  4,3,2,1$

  $\ce{Cu} - 4,3,2,1$

  $\ce{Zn} - 2,1$

Why does $\ce{Fe}$ show not show $+7$ or $+8$ oxidation state?
After $\ce{Fe}$ from $\ce{Co}$ why is there a decrease in number of possible    oxidation states?
Why don't $\ce{Fe,Co,Ni,Cu,Zn}$ show higher oxidation states though they have valence electrons left in $3d$ subshell?


texts:
I have tried this method:

Can anyone suggest me a shorter route?

  Criteria: Benzene has to be produced, it is not available.

Edit : I don't understand why the question has been put on hold. They provide the reason that there may be possibly to many good answers or the question is very broad. As far as my knowledge goes, I haven't received any correct answer that addresses what I have asked.

I would request the authority to reconsider on their decision.


texts: Is the dissolution of sodium acetate trihydate endothermic?

texts:
Sodium acetate trihydrate dissolves in water to its constituent ions:

$$\ce{NaOAc.3H2O (s) ->[H2O] Na+ (aq) + OAc- (aq) + 3H2O (l)}$$

The crystallisation of sodium acetate from a supersaturated solution is well-known to be exothermic. Since dissolution is the reverse of crystallisation, should the enthalpy of dissolution be positive (i.e. an endothermic process)?


texts:
The question says that

  the value of mutual solubility of water and hexane is small. Consult bibliography to find it out.

I can't find it and I'm also concerned as to why the question doesn't include a temperature.


texts: I have copper minerals in rock that has been pulverized. These copper minerals are pure (native copper), chalcocite, chrysacolla, malachite, tenorite, cuprite and azurite. Does anyone know which acids will dissolve which minerals? I need this information as a lab has proposed to use $\ce{HF}$, $\ce{HNO3}$ and $\ce{HClO4}$ to perform an assay and I'm not sure it will work 100%.


texts: Is it wise to use ECPs on light atoms for electronic structure calculations?

texts: So, I have a big organic molecule consisting of $\ce{H}$, $\ce{C}$, $\ce{O}$, and $\ce{N}$ atoms and the goal is to find its equilibrium geometry and US/Vis spectrum. The molecule is so big that I was thinking about reducing the complexity of the calculations by using effective core potentials (say, Stuttgart RLC) on light atoms ($\ce{C}$, $\ce{O}$, $\ce{N}$). However, I'm not sure how trustworthy the results would be comparing to using full-electron bases, thus, I'm looking for some reviews if there are any.


texts: α,β-unsaturated carbonyl compounds and alkyl addition

texts:
In my book it is suggested that in order to add alkyl groups in α,β-unsaturated carbonyl compounds we use organometallic reagents such as organolithium reagents.
In the previous chapters it was suggested that the addition of alkyl groups in carbonyl compounds with saturated chains it is conducted by using secondary amines that produce enamines.

I would like to know if it is possible to add alkyl groups in α,β-unsaturated carbonyl compounds by using secondary amines.


texts: Can the alkyl-oxygen bond in lactones be cleaved in an SN2 reaction?

texts: I understand that nucleophiles typically attack the electrophilic carbonyl carbon of the lactone and open the ring through a nucleophilic acyl substitution. Has there ever been the case where the nucleophiles open the lactone ring by attacking the carbon adjacent to the oxygen (not the carbonyl oxygen) via a SN2 reaction instead? Is there a preferred pathway for certain nucleophiles to take and why so?


texts: Would copper sulfate corrode copper metal over time?

texts: I'm performing electrodeposition experiments with copper electrodes (anode and cathode) and a copper sulfate electrolyte solution. For my project, the cells assembled would need to be stored for a period of months. I was wondering if the copper sulfate can corrode the copper metal and how long it would take? The copper sulfate concentrations range from 5 mM to 100 mM.


texts:
Find the correct order of increasing $\ce{C-O}$ bond length in $\ce{CO}$, $\ce{CO2}$, $\ce{CO3^2-}$.

My solution: as bond length is inversely proportional to the bond order, the order would be $\ce{CO} < \ce{CO2} < \ce{CO3^2-}$. Am I correct?


texts: Computing of strengthening of π-interaction

texts:
I need some practical advise. What would be the easiest approach to compute strengthening or weakening of π-interaction in a bond with multipole-bond character. I'm not really fond of going through coefficients of Kohn–Sham orbitals. I did it on occasion, but it's a lot of work and I just do no have time. Unfortunately the molecules I need to compare have low symmetry ($\ce{C1}$) so I can't make use of symmetry to divide $\sigma$ and $\pi$ contributions. I'm not quite sure but I remember to read that the energy decomposition analysis in ADF could be used to divide in $\sigma$ and $\pi$ components. Let me make it clear, I'm not interested in comparing bond lengths, I need quantitative measure for the strength of $\pi$ interaction: either energy component or relative contribution of $\sigma$ and $\pi$ components orbitals.

I welcome any suggestions concerning methodology and/or software that can help.


texts: I know what the repeating unit is, but what's the monomer in a polycarbonate?


texts: Why does ammonia act as an acid in only the first of these two reactions?

texts:
$$\ce{2Na(l) +2NH3 (g) ->2NaNH2(s) + H2(g)}$$

$$\ce{CH3Cl (alc) +NH3 (alc) -> CH3NH2 (alc) +HCl(alc)}$$

Doesn't ammonia donate a proton in both cases?


texts: Purpose of water bath- rate of formation of precipitate in haloalkane hydrolysis

texts:
In a high school experiment for observing the rate of formation of precipitate with Silver Nitrate in the hydrolysis reaction of different haloalkanes (Chloroalkane, Bromoalkane, Iodoalkane), a water bath is used to equate the temperature of the mixtures before adding the haloalkanes.
If temperature changes occur in any one of these solutions, then it will heat up the water and for this reason the comparison of the rates of reaction will not be accurate. Why aren't the test tubes removed from the solution before the reaction begins?
Wouldn't it be better to conduct each experiment in an individual water bath or with no water bath at all? Am I missing another purpose the water bath serves?


texts: How long does it take to change states of matter?

texts: I'm interested to know how long it takes to change states of matter and why it takes the time that it does.  For example, what is the very quickest that we could freeze a packet of chicken breasts?  In the food industry, flash freezing is often used to prevent damage from occurring by freezing meat very quickly.  But why does it take the time that it does?  Would it be possible to freeze my packet of chicken in say, a nano second instead of a few minutes?


texts: How to make a sample in ppm? (not a specific compound, only the sample)

texts:
Is soaking 1000 mg tea powder in 0.1 L water for about 12 - 24 hours, can be considered as 10000 ppm tea sample?
Could anyone give me reference from a journal or something similar, about my question topic?
Really appreciate any help you can provide.


texts:
I was recently asked to find the total molar mass of a gold and palladium alloy, given the total number of atoms in the compound.
The method was to simply convert the total number of atoms to the total number of moles by using Avogadro's number as the conversion factor.

But as I understand it,  Avogadro's number and his concept only works if all the atoms are the same.  If multiple types of atoms are present in a group of $6.022\times10^{23}$ of them,  how could the different masses add up to a mole?


texts: I know that the orbitals of nitrogen overlap better with the 1s orbitals of hydrogen, but I don't know how to use this information to say why ammonia is stronger than $\ce{PH3}$.


texts:
On Wikipedia, it says that polyethylene terephthalate (PET) decomposes at temperatures above 350°C.
What are these decomposition products? I read further that acetaldehyde is produced, but is that the only decomposition product?

Also, what compounds are produced when PET is burned? ($\ce{+O2->?}$)


texts:
I am trying to understand the synthesis of nitrocellulose.
A mixture of sulfuric acid and nitric acid is used to nitrate cellulose. The sulfuric acid acts as a catalyst, producing $\ce{NO2^{+}}$ ions from the nitric acid which bind at certain sites on the cellulose chain to nitrate it. So nitrate salts can be used instead of nitric acid because all you really need are the nitrate ions. The sulfuric acid acts by protonating nitric acid to yield nitronium and hydronium ions. If so, wouldn't any sufficiently strong acid, such as hydrochloric acid, do just as well.

As long as the Ka for that acid is higher than nitric acid's, it would work the same right?
Also, wouldn't very small amounts of nitronium ion be present without the sulfuric acid anyway?
Could one prepare nitrocellulose using only nitric acid if it were soaked for a much longer time?


texts: What defines the oxidizing/reducing power of a coordination compound?

texts:
For example, I came across a problem in which I was asked to determine whether the complex $\ce{[Cr(H2O)6]Cl2}$ is an oxidizing or reducing agent.

How should I proceed? My teacher told me its the EAN number that defines this. What are your views?


texts:
In our chemistry lecture today on UV/vis-spectroscopy, we discussed the origin of colour in conjugated molecules due to electronic transitions from lower-energy molecular orbitals to higher-energy molecular orbitals. One of the examples we talked about was the origin of the orange colour of carrot. The lecturer mentioned that carrots appear orange as it contains conjugated molecules that absorbs blue light, resulting in the complementary orange colour being emitted. This blue light is used to excite electrons from π MOs to π* MOs in the molecule. One of my classmates asked what happens to the excited electron when it falls back to the ground state, wouldn't it cause blue-light photons to be emitted?

To this, the lecturer replied that perhaps, there is de-excitation of the electrons through other pathways, such as through molecular vibrations (i.e. kinetic energy of the molecules). However, he also was not so sure about the matter. Thus, I would like to seek clarification on how these excited electrons de-excite after initial excitation.


texts:
Consider the NMR of Brominated Pyridine shown below:

When I looked at the NMR data, I was confused because I thought that H2 would also be split in the meta position by H6 but the data says that this is not present in the overall NMR Spectra, although from previous NMR lessons I thought that this would be observed.

Why does H2 not couple to H6 in the NMR shown above?


texts: Why and how does carbon hybridize itself according to its need?

texts:
Sometimes carbon forms sp3 orbital and sometimes sp2 and sp. Also, carbon chains are more stable with sp3 orbitals. So, why and how does carbon hybridize itself to other orbitals?
My question is more about stability. It's not about how it is significant to organic chemistry. For example, Methane which has 'sp3' orbitals is stable because of its sigma bonds. But, ethene, which has a pi bond is not stable and is more reactive than methane. So, why does carbon form this 'pi bond' while on the other hand has a better option of a sigma bond.


texts:
Inspired in part by the question boiling point of vodka - given that the exact ingredients of Coca-Cola are kept secret, based on what is known, what would a viable prediction of the boiling point of Coca-Cola be?

Would it be significantly different from related products (e.g. Diet Coke, Coke Zero, etc)?


texts: SN1 vs SN2 in low concentration of nucleophile

texts: Why is SN1 mechanism favoured by low concentration of nucleophilic reagent? It is a first order reaction so shouldn't the reagent be in excess? Also higher the concentration of reagent faster the reaction right?


texts: Absorption and emission at same wavelength?

texts:
Is it possible for a molecule to absorb and emit at the same wavelength? What is the reason behind it?
I’m working on charged tin porphyrins and got the excitation and emission (fluorescence) wavelength around 400 nm.


texts: Why did they ‘split’ this H2+ ion in the ionic equation?

texts:
I am asked this chemistry question in my textbook:

  Write an ionic equation for this reaction:
  $$\ce{Mg(s) + H2SO4(aq) -> MgSO4(aq) + H2(g)}$$

This is my thought process and answer:
$\require{cancel}$
\begin{align}
  \ce{Mg(s) + H2SO4(aq) &-> MgSO4(aq) + H2(g)}\\
  \ce{Mg(s) + H2+(aq) + SO4^{2-}(aq)
    &-> Mg^{2+}(aq) + SO4 ^{2-}(aq) + H2(g)}\\
  \ce{Mg(s) + H2+(aq) + \cancel{\ce{SO4^{2-}(aq)}}
    &-> Mg^{2+}(aq) + \cancel{\ce{SO4^2-(aq)}} + H2(g)}\\\hline
  \ce{Mg(s) + H2+(aq) &-> Mg^{2+}(aq) + H2(g)}
\end{align}

This was the answer:

  $$\ce{Mg(s) + 2H+(aq) -> Mg^{2+}(aq) + H2(g)}$$

Why did they ‘split’ the $\ce{H2+(aq)}$ ion into $\ce{2H+(aq)}$?


texts: Transformed chemical potential of formation: something weird in Alberty 2003

texts:
I am trying to wrap my head around transformed chemical potentials, as described in Thermodynamics of biochemical reactions (R. Alberty, 2003), however, two equations seem to be contradictory in this book.
Lets consider a chemical species $AH_n$, which has n protons. The formation reaction of that species would then be
$$\ce{A^{n-} +nH+<=> AH_n}$$
According to equation 4.4-6 of Alberty 2003, $\Delta_f G$; the Gibbs energy of formation for $\ce{AH_n}$ (under constant temperature and pressure) would be

$$\Delta_f G = \Delta_f G^0 + RT \ln \{\ce{AH_n}\} \tag{4.4-6}$$

Where $\Delta_f G^0$ is the standard Gibbs energy of formation for $\ce{AH_n}$ and $\{\ce{AH_n}\}$ the activity of $\ce{AH_n}$.
According to equation 4.4-8 Alberty 2003, $\Delta_f G'$; the Legendre-transformed Gibbs energy of formation for $\ce{AH_n}$ (under constant temperature and pressure) would be

$$\Delta_f G' = \Delta_f G'^0 + RT \ln \{\ce{AH_n}\}\tag{4.4-8}$$

Where $\Delta_f G'^0$ is the Legendre-transformed standard Gibbs energy of formation of $\ce{AH_n}$, defined in equation 4.4-9 of Alberty's book as

$$\Delta_f G'^0 = \Delta_f G^0 - n(\Delta_f G^0_{\ce{H^+}} + RT \ln {10}^{-\mathrm{pH}})\tag{4.4-9}$$

that is

\begin{align}\Delta_f G'^0 &= \Delta_f G^0 - n(\Delta_f G^0_{\ce{H+}} - RT \ln (10) \cdot \mathrm{pH}) \\
\Delta_f G'^0 &= \Delta_f G^0 - n \Delta_f G^0_{\ce{H+}} + n \cdot RT \ln (10) \cdot \mathrm{pH}
\end{align}

At an ionic strength of 0; $\Delta_f G^0_{H^+} = 0$. So,

$$\Delta_f G'^0 = \Delta_f G^0 + n \cdot RT \ln (10) \cdot \mathrm{pH}$$

This development seems contradicted by what I can see in equation 4.3-9 of the same book; it states that the Legendre-transformed chemical potential of a pseudo isomer "1" is

$$\mu_1'^0 = \mu_1^0 - N_{H,1} \cdot RT \ln(10) \cdot \mathrm{pH} \tag{4.3-9}$$

where $\mu_1^0$ is the standard chemical potential of pseudo-isomer "$1$" and  $N_{H,1}$ is the number of hydrogen atoms in the pseudo-isomer "1", which is equivalent to the variable $n$ used above. I suppose that in conditions of constant temperature and pressure, chemical potentials are equivalent to Gibbs energies of formation. While this formula is given for a pseudo isomer, it should also be true out of this context, since it has to be true for a group consisting of a single pseudo isomer. What I do not understand is why the sign of the $- N_{\ce{H},1} \cdot RT \ln(10) \cdot \mathrm{pH}$ term is negative given the development of equation 4.4-9. Can someone tell me how those two equations (4.3-9 and 4.4-9) can be true at the same time?


texts:
I'm a high school student with minimal mathematical knowledge about the theory of chemical bond. (I just have a bit of theoretical background). I came across a statement which stated that "The more is the s character in a hybrid orbital, the stronger will be the bond. "
I also came across a statement the "The extent of overlap increases with increase in directionality of bond." (Example : p-p > s-p > s-s reflects the order of the extent of overlap of orbitals keeping the internuclear distance same). What I think is that the more will be the overlap , the stronger will be the bond formed. How can I account for these contradictory statements? I'm confused. Thanks in advance.


texts: Electrolysis of molten Calcium Chloride: Identifying the product

texts:
I was trying to make Calcium metal by electrolyzing molten $\ce{CaCl_2}$. I used a stainless steel spoon and a thick steel wire as electrodes. Then I attached them to a power supply. I placed some $\ce{CaCl_2}$ in the spoon and melted with a gas torch. I then placed the steel electrode in the molten pool and gradually pulled it out. A black glassy substance formed on the rod. I ran water over it and it fizzed as I would expect from Calcium metal, however, when it was exposed to air for a period of time it start to "melt" as it absorbed moisture from the air. As I was breaking it off of the electrode, it shattered and I could see that it was the glassy substance all the way through.

I am trying to figure out what I have made. Could it possibly be a mixture of unreacted $\ce{CaCl_2}$ and a small amount of Calcium?


texts: What is the reaction equation for a mixture of trichloroethanoic acid and dimethylpropanoic acid?

texts:
Write an equation for the reaction you might expect to take place if trichloroethanoic acid, $\ce{Cl3CCO2H}$, $\mathrm{p}K_\mathrm{a} = 0.65$, were added to dimethylpropanoic acid, $\ce{(CH3)3CCO2H}$, $\mathrm{p}K_\mathrm{a} = 5.05$. Explain your answer in terms of the Brønsted–Lowry theory.

I know that $\ce{Cl3CCO2H}$ is the stronger acid as it has a lower $\mathrm{p}K_\mathrm{a}$, however, how can dimethylpropanoic acid be a base?


texts:
Just surface level here, if I had two compounds and wanted to know which one was dipolar, could I just add them to water? If so, would the dipolar substance dissolve while the other compound is unaffected?

Thanks