Questions tagged [hydrogen-bond]
Bond between covalently bound hydrogen atom and atom possessing a lone pair of electrons.
182
questions
2
votes
1answer
43 views
Hydrogen bonding of chlorine [duplicate]
Even though nitrogen is less electronegative than chlorine according to Pauling scale bit why don't it form hydrogen bonding as effective as of nitrogen ? ( Electronegativity valve of N =3.0,Cl=3.2)
4
votes
0answers
40 views
Why mixing water with ethanol produces heat energy? [closed]
Sorry if I'm asking something stupid but I'm trying to understand where this energy gets from. As far as I could find, it is not a reaction as both chemicals left unchanged, so it might have something ...
0
votes
0answers
25 views
Why does energy need to be “compensated” in order for solvation to occur?
I am currently learning about the physical properties of alcohols.
I understand that the main intermolecular forces between alcohols and water are hydrogen bonds. When these two are mixed, the ...
2
votes
1answer
88 views
Boiling point of ethanamide vs propanamide
I just have a question regarding the boiling points of some primary amides. Ethanamide has a boiling point of 222 °C, while propanamide has a lower boiling point of 213 °C. Both amides are capable of ...
4
votes
2answers
147 views
Why dichlormethane is immiscible in water?
As we know like dissolves like. And DCM is a polar solvent and water is too a polar solvent. Also there ought to be a strong hydrogen bonding between the chlorine and hydrogen atoms. So why it's ...
3
votes
0answers
50 views
Diazo Coupling reaction with para substituted phenol?
Usually Diazo coupling occurs at para position until the para position is occupied , in which case coupling occurs at ortho position .
While solving questions I found in both the cases as shown , ...
5
votes
0answers
87 views
Does increasing # of hydrogen bonds decrease the strength of these bonds?
I saw the question, "Is the strength of hydrogen bonding greater in hydrogen peroxide or water?" and it reminded me of a question I had about hydrogen bonding:
If an oxygen on a water has a hydrogen ...
2
votes
0answers
67 views
Hydrogen Bonding in Water (MO theory)
Valence Bond Theory tells us that each of the “sp3” (in reality, 44% s character) oxygen line pairs in water can act as electron donors, but observing the MO diagram for water tells us that the 2 non-...
1
vote
1answer
49 views
Complementary base pairing
In the molecular structure of a DNA it is seen that purines (adenine and guanine) bind with pyrimidines (cytosine, uracil and thymine) through hydrogen bonds, and this is always between a purine and a ...
0
votes
1answer
62 views
Why are hydrogen-bonded compounds (such as NH3) excellent solvents for most lab reagents? [closed]
Hydrogen bonds are said to be one of the strongest molecular interactions in nature. Then why can most substances that interact through hydrogen bondig such as water and $\ce{NH3}$ able to dissolve a ...
5
votes
1answer
138 views
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 ...
0
votes
0answers
10 views
Density change due to hydrogen bonding in water and other compounds [duplicate]
I know that the hydrogen bonding between the water molecules causes water to expand when frozen (compared to water at 4 degrees). Do other compounds that contains hydrogen such as hydrogen sulfide and ...
0
votes
2answers
113 views
What would be the intermolecular forces between the molecules of methanetetrol?
Methanetetrol has the following chemical formula: $\ce{CO4H4}$. It is also referred to as orthocarbonic acid.
Since the molecule has a molecular geometry of a tetrahedron, similar to that of a ...
-2
votes
1answer
61 views
How hydrogen molecule is formed? [closed]
How two hydrogen atoms come close to form a bond ? Textbooks refer to a potential energy diagram but what i cant understand is what is this potential energy if the atoms are neutral . How they come ...
6
votes
1answer
696 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-...
0
votes
1answer
140 views
Dimerisation of HOOC-COOH in non polar solvents
In a textbook I read, the following question is my doubt:
Why is the answer B)? Why do the other molecules not dimerise? How does it work?
(P.S- Why dosen't the B) option only form hydrogen bonds ...
2
votes
2answers
920 views
Stability of geometrical isomers in cycloalkanes
Among the following, which should be the most stable compound?
1)Cis-cyclohexane-1,2-diol
2)Trans-cyclohexane-1,2-diol
3)Cis-cyclohexane-1,3-diol
4)Trans-cyclohexane-1,3-diol
My thought process is-...
1
vote
2answers
842 views
Hydrogen bonds - why not in HCl? [duplicate]
In a textbook1, I found the following clear definition of hydrogen bonds:
The strongest secondary bonding type, the hydrogen bond, is a special case of polar molecule bonding. It occurs between ...
1
vote
0answers
298 views
Why is the intermolecular hydrogen bond between phenol and aniline stronger than the respective hydrogen bonds? [duplicate]
From NCERT class 12 part 1
The way I see hydrogen bonding is that it occurs due to intermolecular charge interaction. The more electronegative nitrogen/oxygen due to the inductive effect the ...
0
votes
1answer
339 views
Why is the melting point of hydrogen fluoride lower than that of ammonia?
The melting point of hydrogen fluoride is -83.6°C, as compared to that of ammonia, which is -77.73°C. How does this make any sense?
Both hydrogen fluoride and ammonia show hydrogen bonding, which "...
7
votes
1answer
115 views
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 ...
1
vote
0answers
1k views
Explain the effect of intramolecular hydrogen bonding on solubilities in cold and hot water?
There is a statement given in my textbook (Cengage, Organic Chemistry (Part 1), page 4.33) which is as follows: (I edited the statement to make it simpler)
One can account for the solubilities of ...
1
vote
2answers
73 views
What is Hydrogen bond Auto-correlation function
Can somebody explain the Hydrogen bond Auto-correlation function in Computational Chemistry (Molecular Dynamics and Simulations) and what does Intermittent and Continuous Hydrogen bond means?
Why ...
4
votes
2answers
471 views
Hydrogen bonding in chloral hydrate
Normally, chlorine doesn't form hydrogen bonds because despite its electronegativity, the size of the atom is such that its electron density is too low to form hydrogen bonds.
However, chlorine forms ...
1
vote
1answer
140 views
Why are highly branched alcohols solid?
Usually branching (or decrease in surface area) leads to increased volatility. But in case of alcohols, my book states that:
The higher alcohols (butanols to decanols) are somewhat viscous, and ...
18
votes
3answers
3k views
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 ...
0
votes
1answer
749 views
Why only F, O and N form Hydrogen Bonds? [duplicate]
Why only fluorine, oxygen and nitrogen can form hydrogen-bonds with the hydrogen of another molecule?
4
votes
0answers
313 views
Hydrogen bond strength of trichloromethane and chloromethane
Chloromethane has a larger dipole moment than trichloromethane. Does that mean that the hydrogen bond (C-H...O type) between chloromethane and acetone is stronger than that of trichloromethane and ...
-1
votes
1answer
133 views
electronegativity and hydrogen bonding [duplicate]
I have a basic idea why, but can someone just confirm, why chlorine isn't able to hydrogen bond despite the fact that it has the same electronegativity value as nitrogen.
1
vote
0answers
37 views
How to characterise lipophilicity?
I was provided with a drug compound which is filling a hydrophobic pocket. The R group is changed and effects on the potency was measured; $\ce{R = -H, -CH3, -CH2F}$ were tested. As expected, the more ...
1
vote
0answers
72 views
How to determine the pH range at which maximum hydrate is present?
Question:
Find the $\mathrm{pH}$ range at which maximum hydrate is present in a solution of oxaloacetic acid (given $\mathrm{pK_a}$ of $\ce{-COOH}$ in the left is $=2.2$ and on the right is $=3.98$)...
4
votes
0answers
586 views
Strongest hydrogen bond between neutral molecules?
It is known that very strong hydrogen bonds can occur in charged systems, such as $\ce{[F-}\ce{-H+-F-]}$, while hydrogen bonds in neutral systems are much weaker in comparison.
What is the strongest ...
12
votes
2answers
757 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 ...
2
votes
1answer
126 views
Will the carboxylate groups of the citrate anion undergo hydrogen bonding?
The citrate anion of trisodium citrate has three carboxylate groups. I am concerned with whether or not there will be hydrogen bonding in water, with hydroxyl groups of other ions or alcohols.
It has ...
5
votes
3answers
2k views
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 ...
1
vote
1answer
777 views
Why is the boiling point of hydrogen sulfide higher than that of hydrogen chloride?
The boiling point of $\ce{H_2S}$ is higher than $\ce{HCl}$. Is this due to the greater number of hydrogen bond that $\ce{H_2S}$ can form compared to $\ce{HCl}$? I found this explanation for the ...
2
votes
0answers
34 views
H-bonding in methanol and methoxyamine [duplicate]
The question was to determine if the substances made H-bonding between themselves and to represent it.
In the following photos i'm showing my doubt about the H-bond in $\ce{CH3OH}$. In the solution (...
1
vote
4answers
13k views
Why H2O is a liquid (water) and H2S is a gas?
I always think about this question.
Is it due to attraction or repulsion or is there something else that makes one of them a gas and the other a liquid (water)?
0
votes
1answer
1k views
Boiling points of HF, HCl, HI [closed]
I'm really confused over how to weigh the molecular mass with intermolecular forces such as hydrogen bonding in HF in terms of figuring out the melting points in relation to each other.
I know that ...
1
vote
2answers
149 views
Is it possible for Cytosine and Hypoxantine to make three hydrogen bonds?
I think the O from Hypoxanthine can bond with one of the Hs in NH2 from Cytosine and the H that is connected to N in Hypoxanthine with the N in Cytosine but is it possible also for the H connected to ...
5
votes
1answer
180 views
Is the surface of glass a fine layer of silanol?
Today we learned in class through a vivid demonstration that water sticks to glass. We were then taught that water sticks to glass because while glass is mainly composed of silicon dioxide, the ...
13
votes
4answers
3k views
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 ...
-1
votes
1answer
3k views
Why is chitin ordinarily insoluble in water, but soluble after deacetylation? [closed]
Chitin is usually insoluble in water. How does its chemical structure explain this?
Furthermore, when chitin undergoes deacetylation, it becomes soluble and forms hydrogen bonds with water. How is ...
4
votes
1answer
7k views
Why is density of water maximum at 4 degree celsius?
Why is density of water maximum at 4 degree celsius?
We were having a discussion to this question in class and I could gather the following points.
1) $H_2O$ exists in a cage like structure in ice ...
0
votes
1answer
2k views
Solubility of CHCl3 in water
Why isn't $\ce{CHCl3}$ soluble in water?
Why doesn't $\ce{CHCl3}$ participate in hydrogen bonding in water like $\ce{CH3CN}$ as $\ce{Cl}$ can make the $\ce{C-H}$ bond polar like $\ce{CN}$ does?
7
votes
1answer
1k views
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?
4
votes
1answer
994 views
Relationship between freezing point depression and hydrogen bonds
Freezing point of a solvent is decreased due to the added solute particles in it. e.g. ions. Therefore electrolytes contribute to lowering freezing point (say for physiological conditions).
If a ...
-2
votes
1answer
82 views
Which oxygen will form a better hydrogen bond?
Which oxygen will form a stronger hydrogen bond , the one in water or the one in hydrogen peroxide ??
According to me , the one in peroxide will form the stronger H bond as the O here being less ...
2
votes
2answers
1k views
How does hydrogen bonding affect the boiling points of chemical compounds?
My main question is why is the boiling point of methanol so much different from that of water?
I understand that both compound are able to develop hydrogen bonding, and obviously water can develop ...
6
votes
2answers
13k views
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 ...
