Questions tagged [hydrogen-bond]

Bond between covalently bound hydrogen atom and atom possessing a lone pair of electrons.

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38
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4answers
883 views

Do symmetric hydrogen bonds in neutral molecules exist?

As far as I know, there have only few truly symmetric hydrogen bonds been observed. Unquestionable is the existence of it in the bifluoride ion, $\ce{[F-H-F]-}$, see also here. There are a couple of ...
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What exactly is hydrogen bonding (and does it really need fluorine, oxygen, or nitrogen)?

I'm not satisfied with the rationale for the intermolecular attraction known as hydrogen bonding. In my book, it states that Hydrogen bonding is a special type of intermolecular attraction between ...
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Is Hydrogen Bonding a Type of Dipole Dipole Interaction?

I understand that dipole dipole forces is due to the attraction of the different partials charges of atoms in different molecules due to their different electro-negativities. For hydrogen bonding, ...
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Why is the boiling point of stibane higher than that of ammonia?

I recently came across the fact that the boiling point of $\ce{SbH3}$ (stibane) is greater than that of $\ce{NH3}$ (ammonia). I was expecting $\ce{NH3}$ to have a greater boiling point as a ...
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Why does hydrogen fluoride have a boiling point so much lower than that of water?

$\ce{F}$ has more unshared electron pairs and is very electronegative, so $\ce{H}$ of another $\ce{HF}$ molecule can $\ce{H}$-bond with it. $\ce{HF}$ has normal boiling point of $\pu{19.5^oC}$ while $...
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Which has stronger hydrogen bonds: water or ice?

As ice is the solid form of water and it has more hydrogen bonds than water, because it's oxygen atoms are precisely tetrahedrally positioned and each oxygen is hydrogen bonded by four neighbouring ...
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Hydrogen bonding in staggered vs eclipsed conformations

In my first semester of organic chemistry, we learned that staggered conformations have lower energy/higher stability. However, my thought is that if you have interacting OH groups, the hydrogen ...
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Strength of hydrogen bonding in phenol or methanol

I wanted to know whether hydrogen bonding is stronger in phenol or methanol. I saw on Wikipedia about the enthalpies of hydrogen bonding in various cases. but could not find the answer to this ...
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Is hydrogen bonding generally defined to include only three period two elements?

Traditionally, hydrogen bonding has been defined to only include interactions between a positively polarized hydrogen and three period-two elements: nitrogen, oxygen, and fluorine. Why was this ...
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Does hydrogen bonding strength correspond to Brønsted basicity in a given medium?

It does seem that there is a correlation. Both are measures of proton affinity. Heck, isn't hydrogen bonding present in the transition states of most acid base reactions (excluding those involving ...
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1answer
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Can an amide nitrogen be a hydrogen bond acceptor?

Can $\ce{N}$ (i.e. main chain $\ce{NH}$s of recognised residues in a peptide or protein) be a hydrogen bond acceptor? It is a well known fact that the main chain $\ce{NH}$s can be a hydrogen bond ...
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Is the strength of hydrogen bonding greater in hydrogen peroxide or water?

When we compare water and hydrogen peroxide's hydrogen bond strength, which one should have the greater one? I know that peroxide has more hydrogen bonds, but when we compare the strength of each ...
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786 views

How to identify hydrogen bonds and other non-covalent interactions from structure considerations?

Chemistry is governed by a wide range of interactions, from ionic and covalent bonding, or other types of strong interactions, towards weaker types of bonding, attraction, or repulsion, that typically ...
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Why can't alcohols form hydrogen-bonded dimers like carboxylic acids?

Carboxylic acids such as acetic acid are capable of forming dimers: I'm wondering why alcohols like ethanol don't generally form dimers. In the diagram below, the oxygen atom on the left ethanol ...
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2answers
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Which intermolecular interaction is dependent on the inverse cube of distance?

The intermolecular interaction that is dependent on the inverse cube of distance between molecules is: hydrogen bond ion-ion interaction ion-dipole interaction London force Inverse ...
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Why is DMSO more polar than other solvents, yet it dissolves ionic compounds worse?

I'm working right now in the solvent importance in ionic character, and I noticed how a binary salt ($\ce{CuCl2}$) dissolved better in methanol than in dimethylsulfoxide, and in contrast, a ...
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Is a hydrogen bond considered to be a van der Waals force?

Is a hydrogen bond considered to be a Van der Waals force?
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How to simulate surface tension?

I am trying to create a water drop simulation for measuring hydrophobicity of surface. I don't know how to simulate the contact angle which is related by younges equation to the surface tensions for ...
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1answer
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Why does hydrogen bonding in salicylic acid make it more acidic?

When salicylic acid deprotonates (losing the proton from the carboxyl group) it forms a hydrogen bond with between the oxygen in the carboxylate anion and the hydrogen in the alcohol group. However, ...
10
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1answer
152 views

Hydrogen bonding in solid bicarbonates

Why is there two different kinds of hydrogen bonding in solid bicarbonates $\ce{NaHCO3}$ and $\ce{KHCO3}$? In both cases we consider anions of each for hydrogen bonding . The anions involved in ...
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1answer
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Why is a ketone not capable of hydrogen bonding among themselves?

The ketone has one oxygen atom in it and there are two lone pairs hanging out, both of which make it seemingly capable of hydrogen bonding. But in reality it is not. Did some research and found this ...
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1answer
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What are the prerequisites in hydrogen bonding?

I know when a hydrogen bond is, but - can hydrogen bonds only occur between two molecules containing hydrogen? Or, only one of the molecules should contain hydrogen and the other one may not contain ...
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Why is HCl not considered to have hydrogen bonding?

A molecule that has hydrogen bonding usually follows these two premises. 1.) There is a hydrogen atom involved 2.) Hydrogen must be bonded to a highly electronegative element which are ...
8
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1answer
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How does intramolecular hydrogen bonding cause the molecules to be separated from each other?

I learnt about intramolecular hydrogen bonding today, which occurs between molecules such as ortho-nitrophenol. What I was told is that in case of intramolecular bonding, the molecules separate from ...
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Does hydrogen peroxide exhibit intramolecular hydrogen bonding interactions?

We know that intermolecular hydrogen bonding is seen in hydrogen peroxide $(\ce{H2O2})$. But is intramolecular H-bonding, i.e. hydrogen bond between an oxygen atom and a hydrogen atom attached to the ...
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1answer
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Is a temperature decrease required for hydrogen bonds to form in water?

As I understand it, increasing the temperature of water causes hydrogen bonds to break. Does this mean that a decrease in temperature is required for the formation of those hydrogen bonds?
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Water and Ice - density

We know that ice has a lower density than water despite both having the same [molecular] mass. I know that as water turns to ice, it expands. As far as I was taught, I know that it has something to do ...
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Non-conventional polymers

IUPAC defines a monomer as, A molecule which can undergo polymerisation thereby contributing constitutional units to the essential structure of a macromolecule. Bearing this in mind, I thought ...
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1answer
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Specific Heat Capacity of Heavy Water

Water has an unusually high specific heat capacity due to it's hydrogen bonds. Why is it that the change in isotope causes a 10% difference in the heat capacity? How does the added neutron in the ...
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How do gelatin and aluminium sulfate strengthen paper?

When wet, the hydrogen bonds between the cellulose chains in paper are disrupted due to the formation of hydrogen bonds with water. This leads to the paper becoming extremely weak. This is the case ...
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How can the hydrogen bonds in solid HF be best represented?

The hydrogen bonds in solid HF can be best represented as: The correct answer is supposed to be (c), but I don't understand why this is so. Does the strength of hydrogen bonding depend on the $\...
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What is a hydrogen bond acceptor and donor?

I recently read about hydrogen bonding. One thing about which I am really confused is how to distinguish between hydrogen bond acceptors and donors. I looked it up on SE and found this post, which ...
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IChO problem involving the condensation point of NF3, NHF2, NH2F

This is a problem from the 2016 International Chemistry Olympiad (IChO): Which of $\ce{NF3}$, $\ce{NHF2}$, and $\ce{NH2F}$ condenses at the lowest temperature? The answer book says that it is $\ce{...
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Does intramolecular hydrogen bonding occur with carbonic acid and geminal diols?

Is an intramolecular hydrogen bond possible in such compounds? What are the requisites to have intramolecular hydrogen bonding?
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Effect of temperature on Hydrogen Bonding?

We had this question in a test and I am not sure of the answer Q. Temperature changes don't effect the extent of inter and intra molecular hydrogen bonding. State true or false. I think that ...
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1answer
738 views

What is the best hydrogen bond acceptor in 2-amino-N-(3-hydroxyphenyl)acetamide?

I was preparing for my first exam in organic chemistry and came across this question. Draw a water molecule that is hydrogen bonded to the best anticipated hydrogen bond acceptor. 2-amino-N-(3-...
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Why is the boiling point of sulfuric acid much higher than that of phosphoric acid?

Why is boiling point of sulfuric acid much higher than that of phosphoric acid? According to the data book, • The boiling point of sulfuric acid is 337 °C (639 °F; 610 K) When sulfuric acid is ...
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1answer
188 views

Hydration number: Carbonic acid in water

Carbonic acid ($\ce{H2CO3}$) is known to be soluble in water, and that this particular compound is unstable, so much so that according to the 2014 article from Berkeley Lab: New Insights on Carbonic ...
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How many hydrogen bonds in these compounds?

We usually get some questions about how many hydrogen bonds these compounds can create, we use it to differentiate between the boiling point of each one of them so it would be great if you could help ...
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1answer
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Length of C-H bonds in hybridized bonding orbitals

What is the effect of hybridization and double-bond formation on the rest of the atoms/molecules attached to the central atom? For example, in a benzene molecule, the Carbon-Carbon bonds are ...
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506 views

Are metals hydrogen bond acceptors or donors?

In a carbonyl or $\ce{-OH}$ group, it's clear the oxygen acts as a hydrogen bond acceptor. Do metals act as hydrogen bond acceptors or donors and if so, how can I tell as what it's acting?
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Hydrogen bonding in alcohols vs amines

Consider an alcohol and an amine compound with roughly the same molar mass. If I understand correctly, the boiling point for the alcohol is greater for two reasons: The $\ce{O-H}$ bond is more polar ...
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815 views

Steric inhibition of resonance vs. hydrogen bonding

I have to compare the acidic strength of these compounds: Now, in A and B hydrogen bonding will be present which will help stabilize the negative charge of the conjugate base. However, the hydroxyl ...
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Physical significance of double-well potential in quantum bonding

I'm currently studying about the hydrogen bond's Potential Energy Surface (PES) pattern. As per literature, single point energy obtained from Density Functional Theory (DFT) using MP2 approximation ...
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Hydrogen bonding relating to molecular orbital theory

In [1, p. 232] here is an explanation of how alcohols hydrogen bond to each other and I do understand how the alcohols form hydrogen bonds to each other: FIGURE 6.15 Water and alcohols are ...
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Does deuterium exhibit hydrogen bonding?

I searched for this on Google but I only got research articles in the SERP. I know of the concept of hydrogen bonds, that they are a special class of van der Waals forces between highly ...
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Strength of intramolecular vs intermolecular hydrogen bonds

Why are intramolecular hydrogen bonds weaker than intermolecular hydrogen bonds?
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1answer
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Can =NH2+ in Arginine's side chain form hydrogen bonding at physiological pH?

I know that at physiological pH, Arginine will have its $\ce{=NH}$ protonated to $\ce{=NH2+}$. I was wondering if this $\ce{=NH2+}$ can still form a hydrogen bond by being a donor? And does the ...
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Why is ice less dense than water?

I know the traditional explanation, which says that ice has large spaces between $\ce{H2O}$ molecules because hydrogen-bonding gives it an open structure. But what does the open structure have to do ...
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Why are amines more soluble than ethers in water?

For example, diethyl ether ($\ce{C2H5OC2H5}$) has a limited solubility of $6.05\rm~\frac{g}{100~mL}$ water at $25\rm~^\circ C$. However, diethylamine ($\ce{(C2H5)2NH}$) is a lot more soluble in water. ...