Grade 12 Physical Sciences · Matter and Materials · Paper 2 (Chemistry)

Organic Chemistry Grade 12

Real Organic Chemistry past paper questions and answers from 2024 to 2025, with each memo split into the ticks examiners give. Try one, mark yourself, and see exactly which skill cost you marks.

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Question 3.2 · May/June 2025 · Paper 2 · National (DBE) · 4 marks

The vapour pressures of compounds A and B are compared.

3.2 How does the vapour pressure of compound A compare to that of compound B? Choose from HIGHER THAN, LOWER THAN or EQUAL TO.

Fully explain the answer.(4) Diagram for question 3.2

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

Organic Chemistry skills

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More Organic Chemistry Grade 12 questions and answers

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4. Question 4.1.3 · November 2025 · Paper 2 · National (DBE) · 2 marks
4.1 Study the three organic reactions I, II and III below. Compounds T and W are organic compounds. R and S are inorganic substances. Consider only the major products.

Reaction I: $HBr(g) + T \to W$
Reaction II: $W + NaOH(aq) \to CH_{3} CH(OH)CH_{2} CH_{3} + R$
Reaction III: $CH_{3} CH(OH)CH_{2} CH_{3} S T + H_{2} O (ℓ)$

Write down the:
4.1.3 TWO names for the type of reaction in reaction I(2)
Show the memo (2 ticks)Memo
1. ✓
  General typeAddition
  1 mark · Write addition reactions and conditions
2. ✓
  Specific typeHydrohalogenation / Hydrobromination
  1 mark · Write addition reactions and conditions
5. Question 2.6.2 · May/June 2025 · Paper 2 · National (DBE) · 2 marks
The letters A to F in the table below represent organic compounds.
2.6 Ethanol reacts with compound C to form an organic compound Z.

Write down the:
2.6.2 STRUCTURAL FORMULA of compound Z(2)
Show the memo (2 ticks)Memo
1. ✓
  Functional group correctZ is ethyl butanoate. The ester functional group –COO– joins the butanoate part (4 C, from butanoic acid) to the ethyl part (2 C, from ethanol): C=O and C–O–C.
  1 mark · Write esterification reactions
2. ✓
  Whole structure correct $CH_{3} CH_{2} CH_{2} COOCH_{2} CH_{3}$ drawn with ALL bonds and H atoms shown (see the memo structure).
  1 mark · Draw structural formulae
6. Question 10.3.2 · May/June 2025 · Paper 1 · National (DBE) · 4 marks
Light of different frequencies is incident on a metal plate. The sketch graph below shows the relationship between the maximum kinetic energy, $E_{k (ma x)}$ , of the photoelectrons and the energy of the incident photons.
10.3 Calculate the:
10.3.2 Value of Y(4)
Show the memo (4 ticks)Memo
1. ✓
  METHOD 1: Formula $E = W_{0} + E_{k (ma x)}$ (or $h f = W_{0} + E_{k (ma x)}$ )
  1 mark · Use the photoelectric equation
2. ✓
  METHOD 1: Work function $= 3, 68 \times 1 0^{- 19} + \dots$
  1 mark · Use the photoelectric equation
3. ✓
  METHOD 1: Kinetic energy $= 3, 68 \times 1 0^{- 19} + 2, 99 \times 1 0^{- 19}$
  1 mark · Use the photoelectric equation
4. ✓
  METHOD 1: Answer $E = 6, 67 \times 1 0^{- 19}$ (J)
  1 mark · Use the photoelectric equation
7. Question 4.2.1 · November 2025 · Paper 1 · National (DBE) · 3 marks
Cricketers at an academy conduct an experiment to determine the relationship between the contact time and the final momentum of a ball for a constant average net force.

A cricket ball of mass $150$ g is thrown horizontally with a certain initial velocity and is struck by a bat so that the ball moves in the opposite direction, as shown in the diagram below. The average net force acting on the ball is horizontal.

The experiment is repeated using the same ball. The average net force and the initial velocity of the ball are kept constant. The contact time between the bat and the ball is changed EACH time. The results obtained are shown in the sketch graph below.
4.2 Calculate the:
4.2.1 Average net force acting on the ball(3)
Show the memo (3 ticks)Memo
1. ✓
  METHOD 1: Change in final momentum (numerator)Gradient $= F_{n e t} = \frac{Δ p _{f}}{Δ ( Δ t )}$
  $= \frac{4 , 5 - 0}{\dots}$
  1 mark · Read a graph of results
2. ✓
  METHOD 1: Change in contact time (denominator) $F_{n e t} = \frac{4 , 5 - 0}{0 , 03 - 0 , 01} = 225$ N
  1 mark · Read a graph of results
3. ✓
  METHOD 1: Answer with direction $F_{n e t} = 225$ N to the right / opposite to the original direction of the ball
  1 mark · Read a graph of results
8. Question 3.4.2 · May/June 2024 · Paper 2 · National (DBE) · 2 marks
The boiling points of some organic compounds are shown in the table below. The atmospheric pressure is $101, 3$ kPa.
3.4 Consider the boiling points below.
3.4.2 Fully explain the answer to QUESTION 3.4.1.(2)
Show the memo (2 ticks)Memo
1. ✓
  Intermolecular forcesC ( $CH_{3} CH_{2} CH_{2} CH_{2} OH$ /butanol) has stronger intermolecular forces than D ( $CH_{3} CH_{2} CH_{2} CHO$ /butanal).
  OR D has weaker intermolecular forces than C.
  OR A ( $CH_{3} CH_{2} CH_{2} CH_{2} C ℓ$ ) is a more polar molecule than D, increasing the intermolecular forces.
  OR The electron density of A is greater than D, increasing the intermolecular forces.
  1 mark · Explain organic boiling point trends
2. ✓
  EnergyMore energy is needed to overcome or break the intermolecular forces (of C / of A).
  OR Less energy is needed to overcome the intermolecular forces of D.
  Accept: Boiling point of C will be more (in relation to C and D/ $118$ °C vs $75$ °C). Accept: Boiling point of D will be less (in relation to A and D).
  1 mark · Explain organic boiling point trends
9. Question 3.3.2 · November 2024 · Paper 2 · National (DBE) · 4 marks
The vapour pressures of different organic compounds are determined at $20$ °C. The vapour pressures of compounds A, B and C are NOT shown in the table.
3.3 Compounds D and E are compared.
3.3.2 Fully explain the difference in the vapour pressures between compounds D and E.(4)
Show the memo (4 ticks)Memo
1. ✓
  Strongest IMF in D: hydrogen bondingCompound D / propanoic acid has hydrogen bonding (dipole-dipole and London forces) between molecules.
  1 mark · Explain organic boiling point trends
2. ✓
  Strongest IMF in E: dipole-dipoleCompound E / butanal has dipole-dipole forces (and London forces) between molecules.
  1 mark · Explain organic boiling point trends
3. ✓
  Compare strength of IMFIntermolecular forces between molecules of compound D / propanoic acid are stronger than intermolecular forces between molecules of compound E / butanal.
  1 mark · Explain organic boiling point trends
4. ✓
  Compare energy neededMore energy is needed to overcome/break intermolecular forces between molecules of compound D / propanoic acid than in compound E / butanal.
  
  OR: Less energy is needed to overcome/break intermolecular forces between molecules of compound E / butanal than in compound D / propanoic acid.
  1 mark · Explain organic boiling point trends
10. Question 2.4.1 · May/June 2024 · Paper 2 · National (DBE) · 3 marks
The letters A to H in the table below represent eight organic compounds.
2.4 Write down the IUPAC name of compound:
2.4.1 E(3)
Show the memo (3 ticks)Memo
1. ✓
  Correct stemhexene (3-ethylhex-3-ene)
  1 mark · Write IUPAC names
2. ✓
  Substituentethyl
  1 mark · Write IUPAC names
3. ✓
  Name completely correct3-ethylhex-3-ene (3-ethyl-3-hexene)
  1 mark · Write IUPAC names

Organic Chemistry Grade 12 videos

Short lessons from South African teachers first. Videos load only when you tap play, to save your data.

Intermolecular Forces grade 11: Different typesKevinmathscience

Introduction to Organic Chemistry Gr 12Kevinmathscience

Types of Organic Molecules grade 12Kevinmathscience

Naming Alkanes Organic Chemistry Grade 12Kevinmathscience

Grade 12 Organic Chemistry: Representing organic compoundsMiss Martins Maths and Science

Isomers Organic Chemistry Grade 12 IntroductionMiss Martins Maths and Science

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