Which topic carries the most marks in the QCE Chemistry external exam?

Chemical equilibrium systems carries 39.0% of the marks across the 12 QCAA papers from 2020 to 2025, ahead of Properties and structure of organic materials on 28.9%.

How are marks split between question types in the QCE Chemistry exam?

Short answer carries 81.8% of the marks and multiple choice carries 18.2% of the marks, measured across 12 papers and 659 marks from 2020 to 2025.

Has the topic balance changed in recent QCE Chemistry papers?

Yes. Chemical synthesis and design moved up 3.3 percentage points between the 2020 to 2022 and 2023 to 2025 papers.

How many past papers is this QCE Chemistry analysis based on?

12 QCAA external papers from 2020 to 2025, covering 209 questions and 659 marks. 3.0% of those marks carry no dot-point mapping and sit outside the percentages.

QCE Chemistry most tested topics

Across the 12 QCAA Chemistry external papers from 2020 to 2025, Chemical equilibrium systems carries 39.0% of the marks against 12.0% for Chemical synthesis and design, so the paper rewards Chemical equilibrium systems more than any other topic. At dot-point level 3.1.2.3 carries 4.3% of paper marks, and 20 of the 120 dot points that the board assesses externally have not appeared in one of these papers. Every percentage below covers the 97.0% of marks that map to a syllabus dot point.

Computed from 12 QCAA Chemistry external papers, 2020 to 2025: 209 questions, 358 question parts and 659 marks.

Unit, topic and dot-point shares below are of the 639 marks that map to a dot point, so each of those tables adds to 100%. 119 of the 358 parts are assessed against more than one dot point, and their 270 marks are divided evenly between the dot points they cover.

What these papers are

Year	Paper	Questions	Marks
2025	Paper 1	29	55
2025	Paper 2	9	55
2024	Paper 1	29	58
2024	Paper 2	8	52
2023	Paper 1	27	57
2023	Paper 2	9	54
2022	Paper 1	27	51
2022	Paper 2	6	49
2021	Paper 1	28	57
2021	Paper 2	5	51
2020	Paper 1	27	60
2020	Paper 2	5	60

Marks by unit

Unit	Share of marks
Unit 3: Equilibrium, acids and redox reactions	59.2%
Unit 4: Structure, synthesis and design	40.8%

Marks by topic

Topic	Share of marks	Papers it appears in	Years
Chemical equilibrium systems	39.0%	12 of 12	6 of 6
Properties and structure of organic materials	28.9%	12 of 12	6 of 6
Oxidation and reduction	20.2%	12 of 12	6 of 6
Chemical synthesis and design	12.0%	12 of 12	6 of 6

Marks by subtopic

Each topic above breaks into the subtopics below, in the same order.

Subtopic	Share of marks	Papers
Factors that affect equilibrium	6.6%	10 of 12
Dissociation constants	6.3%	11 of 12
Equilibrium constants	5.7%	12 of 12
Volumetric analysis	4.6%	7 of 12
Chemical equilibrium	3.7%	9 of 12
Properties of acids and bases	3.4%	10 of 12
pH	3.2%	10 of 12
Acid-base indicators	2.9%	5 of 12
Brønsted-Lowry model	2.6%	10 of 12
Structure of organic compounds	9.7%	12 of 12
Organic reactions and reaction pathways	8.7%	11 of 12
Analytical techniques	4.2%	7 of 12
Organic materials: structure and function	4.1%	10 of 12
Physical properties and trends	2.2%	5 of 12
Redox reactions	8.1%	12 of 12
Standard electrode potential	6.1%	11 of 12
Electrolytic cells	3.1%	6 of 12
Galvanic cells	2.3%	7 of 12
Electrochemical cells	0.5%	3 of 12
Chemical synthesis	7.7%	10 of 12
Macromolecules: polymers, proteins and carbohydrates	4.2%	8 of 12

Marks by dot point

Dot-point numbers and wording are QCAA's own. Where a dot point is written as a list, its items run together here separated by semicolons.

Dot point	Content	Topic	Share of marks	Papers
3.1.2.3	Apply Le Châtelier’s principle to determine the effect changes of temperature, concentration of chemicals, pressure and the addition of a catalyst have on the position of equilibrium and on the value of the equilibrium constant	Chemical equilibrium systems	4.3%	8 of 12
3.1.7.4	Calculate dissociation constants ( $K_a$ , $K_b$ , and $K_w$ ), $pK_a$ , $pK_b$ , and the concentrations of reactants and products. (Formula: $K_a = \frac{[H_3O^+][A^-]}{[HA]}$ ; $K_b = \frac{[BH^+][OH^-]}{[B]}$ ; $K_w = K_a \times K_b$ )	Chemical equilibrium systems	4.1%	8 of 12
4.2.1.2	Describe, using equations, the: production of ammonia by the Haber process; production of sulfuric acid using the contact process; production of ethanol from fermentation and the hydration of ethene; operation of a hydrogen fuel cell under acidic and alkaline conditions	Chemical synthesis and design	3.4%	7 of 12
3.2.4.6	Analyse data, including standard electrode potentials, to make predictions about the spontaneity of a reaction and to compare electrochemical cells	Oxidation and reduction	2.7%	8 of 12
3.1.3.6	Calculate equilibrium constants ( $K_c$ ) and the concentrations of reactants and products. Assume $[reactants]_{initial} = [reactants]_{equilibrium}$ when $K_c$ is very small and state assumption when used. (Formula: $K_c = \frac{[C]^c[D]^d}{[A]^a[B]^b}$ for the reaction $aA + bB \rightleftharpoons cC + dD$ )	Chemical equilibrium systems	2.6%	8 of 12
4.1.4.1	Describe the structural features of: amino acids, tripeptides, monosaccharides and disaccharides; polyethene (LDPE and HDPE), polypropene (syntactic, isotactic and atactic) and polytetrafluorethene (Teflon); polylactic acid (PLA), polyamide (nylon) and polyester	Properties and structure of organic materials	2.6%	8 of 12
3.1.5.3	Calculate pH, hydrogen ion concentration $[H^+(aq)]$ , pOH and hydroxide ion concentrations $[OH^-(aq)]$ for strong acids and bases. (Formula: $pH = -\log_{10} [H^+]$ and $pOH = -\log_{10}[OH^-]$ )	Chemical equilibrium systems	2.5%	9 of 12
4.2.2.1	Describe, using equations, how: addition polymers, including polyethene (LDPE and HDPE), polypropene and polytetrafluorethene, can be produced from their monomers; condensation polymers, including polysaccharides (carbohydrates), polylactic acid (PLA), polyamide (proteins and nylon) and polyester, can be produced from their monomers	Chemical synthesis and design	2.5%	6 of 12
4.1.1.7	Apply IUPAC rules in the nomenclature of organic compounds, up to $C_{10}$ , including simple methyl and ethyl branched chains, for: alkanes, alkenes and alkynes; alcohols (primary, secondary and tertiary); aldehydes and ketones; carboxylic acids; haloalkanes (primary, secondary and tertiary); esters	Properties and structure of organic materials	2.4%	9 of 12
4.1.3.10	Determine reaction pathways, including reagents, condition and chemical equations, given the starting materials and the product/s formed	Properties and structure of organic materials	2.2%	6 of 12
4.2.1.3	Calculate the yield of chemical synthesis reactions by comparing stoichiometric quantities with actual quantities and by determining limiting reagents and/or reaction conditions	Chemical synthesis and design	2.2%	6 of 12
3.1.9.5	Analyse volumetric data, including solubility, conductometric and acid-base titration curves, to determine moles, mass, volume and concentration	Chemical equilibrium systems	2.1%	5 of 12
3.2.1.2	Determine the species oxidised and reduced, and the oxidising agent and reducing agent, in redox reactions	Oxidation and reduction	2.1%	8 of 12
4.1.3.2	Determine, using equations, the reaction of: alkanes with halogens ( $X_2$ ); haloalkanes with halogens ( $X_2$ ), sodium hydroxide and ammonia; alkenes with water, halogens( $X_2$ ), hydrogen ( $H_2$ ) and hydrogen halides ( $HX$ ); alcohols with hydrogen halides ( $HX$ ); carboxylic acid with alcohol to form esters, and with amines to form amides	Properties and structure of organic materials	2.0%	7 of 12
4.1.5.4	Analyse data from spectra, including mass spectroscopy and infrared to determine the identity and structure of organic molecules	Properties and structure of organic materials	2.0%	6 of 12
4.1.2.1	Explain the trends (melting point, boiling point, volatility, solubility in water and organic solvents) within and between homologous series (alkanes, alkenes, alcohols, carboxylic acids) in term of intermolecular and intramolecular bonding, e.g. dispersion forces, dipole-dipole interactions and hydrogen bonds	Properties and structure of organic materials	2.0%	5 of 12
3.2.1.3	Explain that oxidation can be modelled as the loss of electrons from a chemical species, and reduction can be modelled as the gain of electrons by a chemical species; these processes can be represented using balanced half-equations and redox equations (acidic conditions only)	Oxidation and reduction	1.8%	7 of 12
4.1.1.1	Identify organic molecules including alkanes, alkenes, alkynes, alcohols, aldehydes, ketones, carboxylic acids, haloalkanes, esters, amines and amides	Properties and structure of organic materials	1.8%	9 of 12
4.1.1.6	Determine molecular and structural formulas for organic compounds, up to $C_{10}$ , including simple methyl and ethyl branched chains, for: alkanes, alkenes and alkynes; alcohols (primary, secondary and tertiary); aldehydes and ketones; carboxylic acids; amines and amides; haloalkanes (primary, secondary and tertiary); esters	Properties and structure of organic materials	1.8%	7 of 12
3.2.1.7	Analyse data, including displacement reactions of metals, combustion, corrosion and electrochemical processes to determine redox reactions	Oxidation and reduction	1.7%	4 of 12

These 20 dot points carry 48.8% of the paper marks between them. Another 80 assessed dot points share the rest, and 20 of the 120 externally assessable dot points have not been assessed in any of these 12 papers. Content that has not appeared is still examinable.

What has moved between papers

Comparing the 2020 to 2022 papers with the 2023 to 2025 papers, one topic has moved by more than 3.0 percentage points.

Topic	2020 to 2022 share	2023 to 2025 share	Movement
Chemical synthesis and design	10.3%	13.6%	up 3.3 points

How the papers are built

Short answer carries 81.8% of the marks across these 12 papers.

Question type	Share of marks	Marks	Parts
Short answer	81.8%	539	238
Multiple choice	18.2%	120	120

Verb	Share of marks	Marks	Parts
explain	33.7%	222	79
determine	19.1%	126	60
calculate	12.0%	79	26
identify	11.8%	78	49
predict	6.1%	40	14
describe	5.2%	34	14
apply	4.9%	32	13
deduce	3.6%	24	9

What these percentages do not tell you

Where to practise

Every topic above links to its own page of real QCAA questions with marking criteria and average scores attached: Chemical equilibrium systems, Properties and structure of organic materials, Oxidation and reduction and Chemical synthesis and design. For how students actually score on this content, read QCE Chemistry hardest topics, and for the full question bank start at QCE Chemistry.

Syllabus and assessment material referenced in this guide is © State of Queensland (Queensland Curriculum and Assessment Authority), licensed under CC BY 4.0. See our QCAA licensing notice. AusGrader is an independent study tool and is not affiliated with, endorsed by, or operated by the QCAA.