Hydrogen Bonding Examples in Chemistry

Start with the recap, study the fully worked examples, then use the practice problems to check your understanding of Hydrogen Bonding.

This page combines explanation, solved examples, and follow-up practice so you can move from recognition to confident problem-solving in Chemistry.

Concept Recap

Hydrogen bonding is a particularly strong dipole-dipole attraction that occurs when a hydrogen atom covalently bonded to nitrogen, oxygen, or fluorine is attracted to a lone pair on a nearby nitrogen, oxygen, or fluorine atom in another (or the same) molecule.

When hydrogen is attached to a very electronegative atom, nearby molecules feel an unusually strong attraction.

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How to Use These Examples

Read the first worked example with the solution open so the structure is clear.
Try the practice problems before revealing each solution.
Use the related concepts and background knowledge badges if you feel stuck.

What to Focus On

Core idea: Hydrogen Bonding starts by identifying valence electrons, likely charges or sharing, and the structure that follows.

Common stuck point: Students often know a formula related to hydrogen bonding but skip the recognition step: Am I explaining a substance by electron behavior, bond type, molecular shape, polarity, or attractions between particles? That leads to a correct-looking substitution attached to the wrong chemical model.

Sense of Study hint: Ask: Am I explaining a substance by electron behavior, bond type, molecular shape, polarity, or attractions between particles?

Worked Examples

Example 1

medium

Predict whether ammonia

NH_3

is more soluble in water than methane

CH_4

, and justify using hydrogen bonding.

Answer

NH_3 \text{ is far more soluble}

First step

NH_3

has H bonded to N, so it can hydrogen-bond with water.

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Example 2

medium

Sucrose dissolves easily in water. Which functional groups on sucrose are responsible, and what IMF is involved?

Example 3

medium

Explain why HF is a liquid at 19 °C while HCl is a gas at the same temperature.

Example 4

hard

Pentan-1-ol (

C_5H_{11}OH

, bp 138 °C) is far less water-soluble than methanol (

CH_3OH

, fully miscible). Reconcile this with their both having -OH groups.

Example 5

challenge

o-Nitrophenol has a much lower boiling point than p-nitrophenol. Use intramolecular vs intermolecular hydrogen bonding to explain.

Practice Problems

Try these problems on your own first, then open the solution to compare your method.

Example 1

easy

In which molecule can hydrogen bonding occur:

CH_4

H_2O

Example 2

easy

Name the three elements that hydrogen must be bonded to for hydrogen bonding.

Example 3

easy

Does

NH_3

exhibit hydrogen bonding? Answer yes or no.

Example 4

easy

Is hydrogen bonding stronger or weaker than a typical covalent bond?

Example 5

easy

Which has stronger intermolecular forces:

H_2O

H_2S

Example 6

easy

In an HF molecule, which atom carries the partial positive charge?

Example 7

easy

True or false: hydrogen bonding raises the boiling point of a substance.

Example 8

easy

Can two methane (

CH_4

) molecules hydrogen bond with each other?

Example 9

medium

Methanol (

CH_3OH

) and ethane (

C_2H_6

) have similar molar masses. Which has the higher boiling point and why?

Example 10

medium

Rank the boiling points of

H_2O

H_2S

, and

H_2Se

from highest to lowest.

Example 11

medium

Why does ice float on liquid water, in terms of hydrogen bonding?

Example 12

medium

DNA strands are held together by hydrogen bonds between base pairs. Are these bonds easy to separate during replication? Explain briefly.

Example 13

medium

Which can form a hydrogen bond with a water molecule:

CH_4

CH_3OH

, or

CO_2

Example 14

medium

A chemist says HCl shows hydrogen bonding because it contains hydrogen. Identify the error.

Example 15

medium

Acetic acid (

CH_3COOH

) is very soluble in water. Which group is responsible, and what force is involved?

Example 16

medium

Per molecule, can a single water molecule form up to how many hydrogen bonds, and why?

Example 17

medium

Why does liquid water have a higher surface tension than most other liquids?

Example 18

challenge

Ethanol (

C_2H_5OH

, M = 46 g/mol) boils at 78 °C while dimethyl ether (

CH_3OCH_3

, also M = 46 g/mol) boils at -24 °C. Explain the large difference.

Example 19

challenge

Hydrogen fluoride (HF) has a higher boiling point than HCl, HBr, and HI even though it is the lightest. Reconcile this with the usual molar-mass trend.

Example 20

challenge

Glycerol (

C_3H_8O_3

) is far more viscous than ethanol. Using hydrogen bonding, explain why.

Example 21

easy

Does

HCN

(a polar molecule with H bonded to C) participate in hydrogen bonding as a donor?

Example 22

easy

Which atom in a water molecule carries the partial negative charge that can accept a hydrogen bond?

Example 23

easy

Among

HF

HCl

HBr

, and

HI

, which one shows hydrogen bonding?

Example 24

easy

Can a water molecule act as both a hydrogen-bond donor and acceptor?

Example 25

easy

Is hydrogen bonding stronger or weaker than London dispersion forces of similar-size molecules?

Example 26

easy

Which has a higher boiling point: water

H_2O

or hydrogen sulfide

H_2S

Example 27

medium

Acetone

(CH_3)_2CO

has no O-H bonds. Can it still hydrogen-bond with water? Explain.

Example 28

medium

Rank the boiling points of

CH_3F

CH_3OH

, and

CH_4

from highest to lowest.

Example 29

medium

Identify the substance that does NOT hydrogen-bond with itself:

NH_3

CH_3F

H_2O

HF

Example 30

medium

In an ice crystal, each water molecule is hydrogen-bonded on average to how many neighbors?

Example 31

medium

A student claims that any molecule containing nitrogen can hydrogen-bond. Refute this with a counterexample.

Example 32

medium

Approximately how strong is a typical hydrogen bond compared to a covalent O-H bond (about 460 kJ/mol)? Choose: 1%, 5%, 25%, or 75%.

Example 33

medium

Predict whether dimethylamine

(CH_3)_2NH

can hydrogen-bond with itself.

Example 34

medium

Predict whether trimethylamine

(CH_3)_3N

self-hydrogen-bonds.

Example 35

medium

Which would have the higher boiling point: propan-1-ol

CH_3CH_2CH_2OH

or butane

C_4H_{10}

? Both are similar size.

Example 36

medium

Identify the hydrogen-bond donor and acceptor in a mixture of methanol

CH_3OH

and ammonia

NH_3

where methanol donates the H.

Example 37

hard

Water has an unusually high specific heat. Briefly explain using hydrogen bonding.

Example 38

hard

In DNA, adenine pairs with thymine (2 H-bonds) and guanine pairs with cytosine (3 H-bonds). Which base pair is more stable thermally?

Example 39

hard

Carboxylic acids often exist as dimers in the gas phase. Sketch (in words) the hydrogen-bonding pattern in an acetic acid dimer.

Example 40

hard

Why does the boiling point of

H_2O

(100 °C) deviate so sharply from the trend

H_2S

(-60 °C),

H_2Se

(-41 °C),

H_2Te

(-2 °C) when going up the group?

Example 41

hard

A protein's alpha-helix is stabilized mainly by what kind of interaction?

Example 42

challenge

Liquid HF has a boiling point of 19.5 °C while water boils at 100 °C, even though the individual H-F bond is more polar than O-H. Explain.

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Related Concepts

Intermolecular Forces Molecular Polarity

Background Knowledge

These ideas may be useful before you work through the harder examples.

intermolecular forcespolarity