Grade 11 Physical Sciences · Matter and Materials

Identify the intermolecular forces

Name the type of force between molecules, such as London forces, dipole-dipole forces or hydrogen bonds (water has hydrogen bonds).

past paper questions use it: 10 past paper questions use it
videos: 3 videos

Learn it: identify the intermolecular forces

Pick one and watch it, then try the questions below. Videos load only when you tap play.

Intermolecular Forces grade 11: Different typesKevinmathscience

Intermolecular Forces grade 11: Hydrogen bondingKevinmathscience

Intermolecular Forces Grade 11 ChemistryMiss Martins Maths and Science

Now try it on a real exam question

No sign-up. Takes 3 minutes.

Question 1.1 · May/June 2025 · Paper 2 · National (DBE) · 2 marks

1.1 How many types of Van der Waals forces are present between the molecules of

CH_{3} CH_{2} Br

?(2)

Work it out on paper first. Then mark yourself with the official memo, one tick at a time.

More past paper questions: identify the intermolecular forces

Work each one out first, then open the memo and check every tick.

3. Question 1.2 · November 2022 · Paper 2 · National (DBE) · 2 marks
Various options are provided as possible answers to the following questions. Each question has only ONE correct answer.
1.2 Which ONE of the following combinations correctly indicates the STRONGEST intermolecular forces found in ethanoic acid and methyl propanoate respectively?(2)
1. A Ethanoic acid: hydrogen bonds; methyl propanoate: hydrogen bonds
2. B Ethanoic acid: dipole-dipole forces; methyl propanoate: London forces
3. C Ethanoic acid: hydrogen bonds; methyl propanoate: London forces
4. D Ethanoic acid: hydrogen bonds; methyl propanoate: dipole-dipole forces
Show the memo (1 tick)Memo
1. ✓
  Correct optionEthanoic acid has an -OH group (in -COOH), so its strongest forces are hydrogen bonds. Methyl propanoate is an ester: it is polar (C=O) but has no H bonded to O, so it cannot form hydrogen bonds between its molecules; its strongest forces are dipole-dipole forces.
  
  Answer: D
  2 marks · Identify the intermolecular forces
4. Question 1.3 · November 2025 · Paper 2 · Provincial · 2 marks
Various options are provided as possible answers to the following questions. Choose the answer and write only the letter (A–D) next to the question numbers (1.1 to 1.10) in the ANSWER BOOK, for example 1.11 E.
1.3 Which ONE of the following substances have ION DIPOLE FORCES between its molecules?(2)
1. A $H_{2} O$ ( $ℓ$ )
2. B $CO_{2}$ (g)
3. C NaCl (aq)
4. D NaCl (s)
Show the memo (1 tick)Memo
1. ✓
  Choose the correct optionIon-dipole forces act between an ion and a polar molecule. In NaCl(aq) the $Na^{+}$ and $Cl^{-}$ ions are surrounded by polar water molecules.
  NaCl(s) has only ions (ionic bonds, no water molecules); $H_{2} O$ ( $ℓ$ ) has hydrogen bonds; $CO_{2}$ (g) has London forces.
  
  Answer: C
  2 marks · Identify the intermolecular forces
5. Question WE2 · Siyavula Grade 11 Physical Sciences, 4.1 Intermolecular and interatomic forces, Worked example 2 · 3 marks
WE2 Which intermolecular forces are found in the following solution: sodium chloride in water?(3)
Show the memo (3 ticks)Memo
1. ✓
  Sodium chlorideSodium chloride is ionic (the electronegativity difference is $2, 1$ ).
  1 mark · Determine bond and molecule polarity
2. ✓
  WaterWater has polar bonds (the electronegativity difference is $1, 4$ ) and is a polar molecule (its shape is bent or angular).
  1 mark · Determine bond and molecule polarity
3. ✓
  Type of forceThis is an ionic substance interacting with a polar substance. This interaction is an ion-dipole force.
  1 mark · Identify the intermolecular forces
6. Question WE1 · Siyavula Grade 11 Physical Sciences, 4.1 Intermolecular and interatomic forces, Worked example 1 · 3 marks
WE1 Which intermolecular forces are found in carbon tetrachloride ( $CCl_{4}$ )?(3)
Show the memo (3 ticks)Memo
1. ✓
  Bond polarityCarbon has an electronegativity of $2, 5$ and chlorine has an electronegativity of $3, 0$ , so the bond between carbon and chlorine is polar.
  1 mark · Determine bond and molecule polarity
2. ✓
  Molecule polarityCarbon tetrachloride is a tetrahedral molecule. It is symmetrical and so is non-polar overall.
  1 mark · Determine bond and molecule polarity
3. ✓
  Type of forceCarbon tetrachloride is non-polar, so the only kind of force that can exist is induced dipole (London) forces.
  1 mark · Identify the intermolecular forces

Free on Android

Know exactly which skill is costing you marks.

Mark past papers tick by tick in the NavyBlue app. It remembers every mark you lose, shows you the skills to fix first, and picks your next questions.

The NavyBlue app showing a learner's weak skills