HSC Chemistry most tested topics
Across the three NESA Chemistry external papers from 2023 to 2025, Quantitative Analysis carries 11.2% of the marks against 0.3% for Problem Solving, so the paper rewards Quantitative Analysis more than any other topic. At dot-point level 8.2.2 carries 8.1% of paper marks, and 28 of the 88 dot points that the board assesses externally have not appeared in one of these papers. Every percentage below covers the 100.0% of marks that map to a syllabus dot point.
Computed from 3 NESA Chemistry external papers, 2023 to 2025: 113 questions, 130 question parts and 300 marks.
Module, topic and dot-point shares below are of the 300 marks that map to a dot point, so each of those tables adds to 100%. 53 of the 130 parts are assessed against more than one dot point, and their 160 marks are divided evenly between the dot points they cover.
What these papers are
| Year | Exam | Questions | Marks |
|---|---|---|---|
| 2025 | Exam | 37 | 100 |
| 2024 | Exam | 39 | 100 |
| 2023 | Exam | 37 | 100 |
Marks by module
| Module | Share of marks |
|---|---|
| Module 5: Equilibrium and Acid Reactions | 25.9% |
| Module 6: Acid/Base Reactions | 22.1% |
| Module 7: Organic Chemistry | 21.6% |
| Module 8: Applying Chemical Ideas | 19.0% |
| Module 9: Working Scientifically Skills | 11.4% |
Marks by topic
| Topic | Share of marks | Papers it appears in | Years |
|---|---|---|---|
| Quantitative Analysis | 11.2% | 3 of 3 | 3 of 3 |
| Processing Data and Information | 9.6% | 3 of 3 | 3 of 3 |
| Analysis of Organic Substances | 9.4% | 3 of 3 | 3 of 3 |
| Factors that Affect Equilibrium | 9.2% | 3 of 3 | 3 of 3 |
| Solution Equilibria | 7.3% | 3 of 3 | 3 of 3 |
| Analysis of Inorganic Substances | 6.8% | 3 of 3 | 3 of 3 |
| Using Brønsted–Lowry Theory | 6.7% | 3 of 3 | 3 of 3 |
| Calculating the Equilibrium Constant | 6.3% | 3 of 3 | 3 of 3 |
| Alcohols | 5.4% | 3 of 3 | 3 of 3 |
| Reactions of Organic Acids and Bases | 4.6% | 3 of 3 | 3 of 3 |
| Properties of Acids and Bases | 4.2% | 3 of 3 | 3 of 3 |
| Products of Reactions Involving Hydrocarbons | 3.9% | 3 of 3 | 3 of 3 |
| Static and Dynamic Equilibrium | 3.2% | 3 of 3 | 3 of 3 |
| Chemical Synthesis and Design | 2.8% | 3 of 3 | 3 of 3 |
| Polymers | 2.7% | 2 of 3 | 2 of 3 |
| Hydrocarbons | 2.6% | 3 of 3 | 3 of 3 |
| Nomenclature | 2.3% | 3 of 3 | 3 of 3 |
| Analysing Data and Information | 0.8% | 1 of 3 | 1 of 3 |
| Conducting Investigations | 0.7% | 1 of 3 | 1 of 3 |
| Problem Solving | 0.3% | 1 of 3 | 1 of 3 |
Marks by dot point
Dot-point numbers and wording are NESA'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 |
|---|---|---|---|---|
| 8.2.2 | investigate the processes used to analyse the structure of simple organic compounds addressed in the course, including but not limited to: – proton and carbon-13 NMR – mass spectrometry – infrared spectroscopy (ACSCH130) | Analysis of Organic Substances | 8.1% | 3 of 3 |
| 5.2.1 | investigate the effects of temperature, concentration, volume and/or pressure on a system at equilibrium and explain how Le Chatelier’s principle can be used to predict such effects, for example: – heating cobalt(II) chloride hydrate – interaction between nitrogen dioxide and dinitrogen tetroxide – iron(III) thiocyanate and varying concentration of ions (ACSCH095) | Factors that Affect Equilibrium | 7.4% | 3 of 3 |
| 9.4.2 | apply quantitative processes where appropriate | Processing Data and Information | 6.4% | 3 of 3 |
| 5.3.2 | perform calculations to find the value of and concentrations of substances within an equilibrium system, and use these values to make predictions on the direction in which a reaction may proceed (ACSCH096) | Calculating the Equilibrium Constant | 5.6% | 3 of 3 |
| 5.4.4 | derive equilibrium expressions for saturated solutions in terms of and calculate the solubility of an ionic substance from its value | Solution Equilibria | 4.5% | 3 of 3 |
| 6.3.4 | calculate and apply the dissociation constant () and () to determine the difference between strong and weak acids (ACSCH098) | Quantitative Analysis | 4.2% | 3 of 3 |
| 7.3.1 | investigate, write equations and construct models to represent the reactions of unsaturated hydrocarbons when added to a range of chemicals, including but not limited to: – hydrogen () – halogens () – hydrogen halides () – water () (ACSCH136) | Products of Reactions Involving Hydrocarbons | 3.4% | 3 of 3 |
| 9.4.1 | select qualitative and quantitative data and information and represent them using a range of formats, digital technologies and appropriate media (ACSCH004, ACSCH007, ACSCH064, ACSCH101) | Processing Data and Information | 3.1% | 3 of 3 |
| 6.3.2 | investigate titration curves and conductivity graphs to analyse data to indicate characteristic reaction profiles, for example: – strong acid/strong base – strong acid/weak base – weak acid/strong base (ACSCH080, ACSCH102) | Quantitative Analysis | 2.8% | 3 of 3 |
| 8.1.2 | conduct qualitative investigations – using flame tests, precipitation and complexation reactions as appropriate – to test for the presence in aqueous solution of the following ions: – cations: barium (), calcium (), magnesium (), lead(II) (), silver ion (), copper(II) (), iron(II) (), iron(III) () – anions: chloride (), bromide (), iodide (), hydroxide (), acetate (), carbonate (), sulfate (), phosphate () | Analysis of Inorganic Substances | 2.8% | 3 of 3 |
| 8.3.1 | evaluate the factors that need to be considered when designing a chemical synthesis process, including but not limited to: – availability of reagents – reaction conditions (ACSCH133) – yield and purity (ACSCH134) – industrial uses (eg pharmaceutical, cosmetics, cleaning products, fuels) (ACSCH131) – environmental, social and economic issues | Chemical Synthesis and Design | 2.8% | 3 of 3 |
| 6.3.1 | conduct practical investigations to analyse the concentration of an unknown acid or base by titration | Quantitative Analysis | 2.7% | 3 of 3 |
| 6.2.2 | calculate pH, pOH, hydrogen ion concentration () and hydroxide ion concentration () for a range of solutions (ACSCH102) | Using Brønsted–Lowry Theory | 2.3% | 3 of 3 |
| 8.1.4 | conduct investigations and/or process data to determine the concentration of coloured species and/or metal ions in aqueous solution, including but not limited to, the use of: – colourimetry – ultraviolet-visible spectrophotometry – atomic absorption spectroscopy | Analysis of Inorganic Substances | 2.1% | 3 of 3 |
| 6.1.3 | predict the products of acid reactions and write balanced equations to represent: – acids and bases – acids and carbonates – acids and metals (ACSCH067) | Properties of Acids and Bases | 2.1% | 3 of 3 |
These 15 dot points carry 60.3% of the paper marks between them. Another 45 assessed dot points share the rest, and 28 of the 88 externally assessable dot points have not been assessed in any of these 3 papers. Content that has not appeared is still examinable.
What has moved between papers
Comparing the 2023 papers with the 2025 papers, five topics have moved by more than 3.0 percentage points.
| Topic | 2023 share | 2025 share | Movement |
|---|---|---|---|
| Factors that Affect Equilibrium | 9.5% | 13.5% | up 4.0 points |
| Calculating the Equilibrium Constant | 7.8% | 1.5% | down 6.3 points |
| Alcohols | 9.8% | 1.7% | down 8.1 points |
| Products of Reactions Involving Hydrocarbons | 1.0% | 8.3% | up 7.3 points |
| Polymers | 0.0% | 5.0% | up 5.0 points |
How the papers are built
Short answer carries 80.0% of the marks across these 3 papers.
| Question type | Share of marks | Marks | Parts |
|---|---|---|---|
| Short answer | 80.0% | 240 | 70 |
| Multiple choice | 20.0% | 60 | 60 |
| Verb | Share of marks | Marks | Parts |
|---|---|---|---|
| explain | 22.0% | 66 | 20 |
| calculate | 19.7% | 59 | 15 |
| justify | 11.0% | 33 | 7 |
| identify | 7.3% | 22 | 5 |
| draw | 7.0% | 21 | 5 |
| determine | 6.0% | 18 | 4 |
| outline | 2.7% | 8 | 3 |
| predict | 2.3% | 7 | 1 |
What these percentages do not tell you
Where to practise
Every topic above links to its own page of real NESA questions with marking criteria and average scores attached: Quantitative Analysis, Processing Data and Information, Analysis of Organic Substances, Factors that Affect Equilibrium, Solution Equilibria, Analysis of Inorganic Substances, Using Brønsted–Lowry Theory, Calculating the Equilibrium Constant, Alcohols, Reactions of Organic Acids and Bases, Properties of Acids and Bases, Products of Reactions Involving Hydrocarbons, Static and Dynamic Equilibrium, Chemical Synthesis and Design, Polymers, Hydrocarbons, Nomenclature, Analysing Data and Information, Conducting Investigations and Problem Solving. For how students actually score on this content, read HSC Chemistry hardest topics, and for the full question bank start at HSC Chemistry.
Frequently asked questions
Which topic carries the most marks in the HSC Chemistry external exam?
Quantitative Analysis carries 11.2% of the marks across the 3 NESA papers from 2023 to 2025, ahead of Processing Data and Information on 9.6%.
How are marks split between question types in the HSC Chemistry exam?
Short answer carries 80.0% of the marks and multiple choice carries 20.0% of the marks, measured across 3 papers and 300 marks from 2023 to 2025.
Has the topic balance changed in recent HSC Chemistry papers?
Yes. Factors that Affect Equilibrium moved up 4.0 percentage points, Calculating the Equilibrium Constant moved down 6.3 percentage points, Alcohols moved down 8.1 percentage points, Products of Reactions Involving Hydrocarbons moved up 7.3 percentage points and Polymers moved up 5.0 percentage points between the 2023 and 2025 papers.
How many past papers is this HSC Chemistry analysis based on?
3 NESA external papers from 2023 to 2025, covering 113 questions and 300 marks. 0.0% of those marks carry no dot-point mapping and sit outside the percentages.
Sources
- HSC Chemistry Examination, NESA, 2025. 3 papers, 2023 to 2025, covering 113 questions and 300 marks. Listed individually in the table at the top of this guide. Dot-point numbering follows the current NESA Chemistry syllabus.
Syllabus and assessment material referenced in this guide is used under licence, © Copyright NSW Education Standards Authority. See our NESA licensing notice. The NSW Education Standards Authority (NESA) does not endorse this product or service. NESA takes no responsibility for any errors in the reproduction of NESA Materials. Any sample examination papers or model answers accompanying the NESA Materials are not part of the NESA Materials and are in no way endorsed or authorised by NESA.
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