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21 votes
Accepted

Why is the boiling point of stibane higher than that of ammonia?

Though it does go against your intuition, you've actually mentioned the answer in your question. Stibane has a higher boiling point than ammonia/azane on account of van der Waals interactions (owing ...
paracetamol's user avatar
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18 votes

Do symmetric hydrogen bonds in neutral molecules exist?

This question crossed my mind during a lab today because we were making $\ce{Ni(dmg)2}$, which is shown below. Well first, this is charged in some sense, but it is net-neutral. Also, the ...
jheindel's user avatar
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18 votes

Do symmetric hydrogen bonds in neutral molecules exist?

It appears that, perhaps, water may have symmetric hydrogen bonds between oxygen atoms, but it would take at least 60 GPa of pressure, to make water to bond like that. I guess water stops being ...
Mithoron's user avatar
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15 votes
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How to identify hydrogen bonds and other non-covalent interactions from structure considerations?

It is safe to say that there will always be intermolecular forces at play. At the time where you will consider these you should already have a good idea about the molecules involved in your system. ...
Martin - マーチン's user avatar
13 votes

Is there intramolecular hydrogen bonding in salicylaldehyde?

It can indeed hydrogen bond, this can (to a certain extent) be observed by NMR. Due to the internal hydrogen bonding, the phenolic proton is surprisingly consistent, and shows no dependence on ...
NotEvans.'s user avatar
  • 17.2k
13 votes

Solubility of ortho- and para-nitrophenol in benzene

It turns out that the opposite of what happens in polar solvents takes place when a non-polar solvent is used. At the same temperature, o-nitrophenol is more soluble in benzene than it's m and p ...
Aniruddha Deb's user avatar
13 votes
Accepted

Does ammonia exhibit hydrogen bonding in its gaseous state?

The paper[1] referenced by Nilay Ghosh says that, it is well known that hydrogen bonds commonly exist in ammonia clusters and play an important role and gives a picture of some of the clusters that ...
James Gaidis's user avatar
13 votes

Why does potassium bifluoride exist whereas bichloride does not?

The bichloride ion $\ce{HCl2^-}$ does exist, but it requires other environment than usual solutions in water. E.g. solution of $\ce{[N(CH3)4]Cl}$ salt and undissociated $\ce{HCl(solv)}$ in ...
Poutnik's user avatar
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11 votes

Do symmetric hydrogen bonds in neutral molecules exist?

In Schaefer's paper,[1] which you linked, the authors describe nitromalonamide as being the compound with the lowest calculated barrier to intramolecular proton transfer, or tautomerisation. Earlier ...
orthocresol's user avatar
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11 votes
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Are there any other elements that get less dense in their solid state?

Your terminology is a little off: water isn't an element. There isn't really a simple single explanation of why some solids are less dense than their associated liquids. The general explanation (which ...
matt_black's user avatar
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11 votes
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Which dicarboxylic acid has the most acidic hydrogen?

The $\mathrm pK_\mathrm a$ of the $\ce{CH2}$ group in a dicarbonyl compound is roughly $10$, whereas the $\mathrm pK_\mathrm a$ of a carboxylic acid is roughly $5$. For example, dimethyl malonate has ...
orthocresol's user avatar
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11 votes
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Why can't alcohols form hydrogen-bonded dimers like carboxylic acids?

The strength of a hydrogen bond somewhat depends on the $\ce{X-H\bond{...}X}$ angle that the hydrogen-bonding hydrogen forms with the two electronegative elements $\ce{X}$. In our case, carboxylic ...
Jan's user avatar
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11 votes

Is a temperature decrease required for hydrogen bonds to form in water?

You are right, in a sense. A more accurate statement would be that as the temperature decreases, the average lifetime of a hydrogen bond increases. Thus, on average the liquid/solid/molecule will be ...
jheindel's user avatar
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11 votes
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Why hydrogen bonding in some acids make them a stronger acid when it is present even before deprotonation?

Some of the conformers of salicylic acid are given below, all of which are planar in configuration.$\mathrm{^{[1]}}$ Although the compound can adopt several conformations the first conformer(in the ...
Rishi's user avatar
  • 477
10 votes
Accepted

Why isn't Indigo soluble in water?

True, Indigo can form hydrogen bonds, but with what? Is it water? Nope. It makes hydrogen bonds with itself. This makes the molecule incapable of bonding with water. Not only that, but the molecule ...
Pritt says Reinstate Monica's user avatar
10 votes
Accepted

Do amines or alcohols have stronger intermolecular hydrogen bonds?

The boiling point of non-ionic compounds are highly depend on their H-bonding abilities. For example, boiling point of water (molar mass: $\pu{18.02 g/mol}$) is $\pu{100 ^\circ C}$ at $\pu{1 atm}$ ...
Mathew Mahindaratne's user avatar
10 votes

Do amines or alcohols have stronger intermolecular hydrogen bonds?

Mathew Mahindaratne has provided analysis based on experimental values of the boiling points of the two compounds. I would like to offer a different view using bonding analysis. Before I begin ...
Tan Yong Boon's user avatar
9 votes
Accepted

Hydrogen bonding in staggered vs eclipsed conformations

Disclaimer: I am not a computational chemist, I am completely new to this stuff. Just a humble student of @pentavalentcarbon However, my thought is that if you have interacting OH groups, the ...
getafix's user avatar
  • 8,495
9 votes

Boiling points of Butan-2-ol and Butan-1-ol

You have certainly understood the main idea. In general the boiling point of a substance is determined by the way the molecules come together. The closer they are, the bigger are the intermolecular ...
Αντώνιος Κελεσίδης's user avatar
9 votes
Accepted

What is a hydrogen bond acceptor and donor?

Dissenter's answer which you linked appears to be wrong (as of now). I have left a comment. The conventional way in which we talk about hydrogen bond acceptors/donors is: in a hydrogen bond $\ce{X-H.....
orthocresol's user avatar
  • 71.4k
8 votes
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Why do Asn-Ser and Gln-Thr have different H bonding patterns?

I don't have the textbook you've gotten this from, but unless there's a statement to the contrary, I suspect these are intended as examples of hydrogen bonding, rather than an exhaustive list of the ...
R.M.'s user avatar
  • 4,933
8 votes
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IChO problem involving the condensation point of NF3, NHF2, NH2F

The interactions do not limit to only dipole-dipole, which means positive charge is not everything. What's special about $\ce{NF3}$? It has no hydrogens. As a result, it cannot form hydrogen bond, ...
Huy Ngo's user avatar
  • 498
8 votes
Accepted

Which is more soluble in water, HF or SO2?

There are a couple different forces at play here. One big difference between the compounds is that $\ce{SO2}$ is much more volatile, with a boiling point of $\pu{-10 ^\circ C}$; in other words it's a ...
airhuff's user avatar
  • 17.5k
8 votes

Which has stronger hydrogen bonds: water or ice?

The quick answer is that ice has stronger hydrogen bonds than liquid water on average.$\require{mediawiki-texvc}%for angstrom unit$ As has already been brought up, this question is not easy to answer ...
jheindel's user avatar
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8 votes
Accepted

Can =NH2+ in Arginine's side chain form hydrogen bonding at physiological pH?

Yes, the arginine side chain is an excellent hydrogen bond donor. Charged N-H groups are even better hydrogen bond donors than the corresponding neutral N-H groups. Here is an article that gives ...
Karsten's user avatar
  • 40.7k
8 votes
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Solubility of ortho- and para-nitrophenol in benzene

The nitrophenols have completely different physical behavior based on the position of nitro group: $$ \begin{array}{c|ccc} \hline \text{Compound} & \text{Melting point} & \text{Boiling point} ...
Mathew Mahindaratne's user avatar
8 votes

Why does potassium bifluoride exist whereas bichloride does not?

The bichloride ion, including isolated salts, has in fact been known since 1954 [1]; but it appears to require relatively bulky counterions whereas bifluoride has a broader range of stable salts. To ...
Oscar Lanzi's user avatar
  • 58.6k
7 votes

Why are amines more soluble than ethers in water?

Diethyl Ether can accept hydrogen bonds readily, and you are correct in pointing out it would be better than diethylamine at doing such. However, diethylamine can also donate a hydrogen bond, giving ...
Lighthart's user avatar
  • 6,659
7 votes

Which intermolecular interaction is dependent on the inverse cube of distance?

2 The ion-ion or charge-charge interaction is given by $$ V_{\text{cc}} = \frac{Z_{i}Z_{j}e^{2}}{4\pi\epsilon_{0}} \frac{1}{|\mathbf{R}_{i} - \mathbf{R}_{j}|} $$ and is therefore proportional to $R^...
pentavalentcarbon's user avatar
7 votes

Explain volume contraction in mixtures of alcohol and water

Liquid water can be thought of as having an average configuration that tends to be an open, almost crystalline structure, somewhat like that for hexagonal ice crystals $\mathrm{^{[1,2,3]}}$. This ...
airhuff's user avatar
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