How to Ace VCE Chemistry: Insights from the 2025 Examiner's Report

VCE Chemistry rewards students who combine accurate calculations with precise chemical language. The VCAA's examiner's report shows exactly where students across the state gained and lost marks, which makes it one of the most useful revision tools available.

This guide breaks down the 2025 VCE Chemistry examiner's report question by question. It covers how students performed in each section, which questions were easiest and hardest, and the specific mistakes that cost marks. For the previous year's analysis, see our 2024 VCE Chemistry examiner's report breakdown.

Key Takeaways

• Students averaged 59% correct on the multiple-choice section. Fuels and sustainability questions were answered well, while electrochemistry (51%) caused the most trouble.
• In three multiple-choice questions (2, 7 and 8), a wrong answer was more popular than the correct one. The hardest was Question 7 (24% correct).
• In Section B, students averaged about 49% of the marks. Mass spectrometry and naming structures were particularly weak: 90% scored zero on Question 4c.iii.
• Calculations were generally well handled. Marks were most often lost on explanations, units and answering in the required form (moles instead of concentration, names instead of formulas).
• The 6-mark green chemistry and ethics question (7b) averaged 3.6 out of 6, which shows that a clear structure pays off.

VCE Chemistry Examination Structure

VCE Chemistry has a single end-of-year examination with two sections.

The whole exam runs for 2 hours and 30 minutes (plus 15 minutes of reading time), is worth 120 marks and contributes 50% of the study score. School-assessed coursework makes up the other 50%.

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Easiest and Hardest Questions in the 2025 Exam

Easiest questions

• Section A, Question 5 (93% correct): Calculating a calibration factor using CF = VIt/ΔT.
• Section A, Question 1 (92% correct): Recognising that biomethane is renewable and natural gas is not.
• Section B, Question 6c.i (90% full marks): Recognising that a higher temperature increases the rate of reaction.

Hardest questions

• Section A, Question 7 (24% correct): 60% chose A. The question asked what moves through the polymer/gel electrolyte. That is metal ions, not electrons, which flow through the external wire.
• Section A, Question 8 (29% correct): 53% chose C. Calculating each circuit's voltage shows circuit A generates 3.60 V, compared with 3.10 V for circuit C.
• Section B, Question 4c.iii (90% scored zero): Writing a fragment ion formula that clearly showed the ³⁷Cl isotope and a single positive charge.
• Section B, Question 4f.i (85% scored zero): Drawing the molecule in skeletal form.

Section A: Multiple-Choice Question Breakdown

The table below shows each Section A question, its topic, the correct answer, the percentage of students who answered correctly and the most common wrong answer, as published in the 2025 examiner's report.

Source: VCAA, 2025 VCE Chemistry external assessment report. Topic labels are our own.

Note: For Question 10, all four options were accepted. Fermentation of glucose involves both oxidation and reduction, which made statement I ambiguous, and no option listed statements I, II and III together.

Performance by Area of Study

Key Takeaways From Section A

• Strongest performance: Calibration (Q5), renewable fuels (Q1), renewable feedstocks (Q21) and the circular economy (Q4) were answered well.
• Electrochemistry was the weakest area: Students struggled with ion movement through an electrolyte (Q7), voltages in circuits (Q8) and artificial photosynthesis (Q18).
• Scientific skills were tested in unfamiliar ways: Only 34% correctly identified the equipment with the highest resolution (Q19). The examiners noted confusion between resolution as a number and resolution as a property of an instrument.

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What Section A Taught Us: Skills, Advice and Common Mistakes

Key Skills to Focus On

• Units and scientific notation: The most common error in Question 2 was a unit error. The answer was 1.9 × 10⁶ J, and 35% chose B.
• Manipulating equilibrium constants: Reversing an equation inverts K, and doubling the coefficients squares it (Q15).
• Using the electrochemical series: Predicting which metals react with water, and comparing cell voltages, depends on reading E° values carefully (Q8 and Q9).
• Chemical tests: Acidified dichromate oxidises aldehydes (orange to green) but not tertiary alcohols. Only 41% got Question 27.

Advice to Students From the Examiner's Report

• Read exactly what the question asks: In Question 7, the words "through the polymer/gel electrolyte" were the key to the answer.
• Know the language of measurement: A higher resolution means an instrument can detect smaller changes (Q19). Random errors scatter data on both sides of a line of best fit, while systematic errors can't be identified without a reference line (Q20).
• Use the stem's information: In Question 28, the stem said the vanillin contained significant impurities, which ruled out option B. Impurities give a lower, broader melting point range.

Common Mistakes in Section A

• Bond energies (Q3): For an overall exothermic reaction, breaking bonds requires less energy than is released when new bonds form. 22% chose D.
• Scaling ΔH (Q6): Dividing the whole equation by 6 also divides ΔH by 6, giving +473.3 kJ. 29% chose C.
• Catalysts (Q14): Catalysts lower the activation energy, so a greater proportion of particles have enough energy for a successful collision. 25% chose B.
• Energy efficiency (Q17): Both benefits reduce wasted heat energy, so both meet the principle of design for energy efficiency. 34% chose B.
• Iodine number (Q29): A triglyceride reacting with 6 mol of iodine has two C=C bonds in each fatty acid, so the answer was linoleic acid. 32% chose A.

Section B: Short-Answer and Extended-Response Breakdown

The table below shows each Section B question, its topic and the percentage of students who received each mark, along with the average mark.

Source: VCAA, 2025 VCE Chemistry external assessment report. Topic classifications are our own.

Performance by Area of Study

Averages are calculated from the published per-question averages and are approximate.

Key Observations From the Examiner's Report

• Strongest performance: Questions 6c.i (rate and temperature, 90% full marks), 3a (reversible reactions, 88%) and 4c.i (base peak, 86%) were answered best.
• Most challenging questions: Questions 4c.iii (90% scored zero), 4f.i (85%), 6f (83%) and 6b (78%) were the hardest. They required a precise formula, a skeletal structure, a percentage calculation and the exact colour of an end point.
• Questions 2, 4, 5 and 6 were the toughest overall: Each averaged about 43–45% of the marks. They covered electrolysis, organic analysis, medicinal chemistry and a redox titration investigation.

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What Section B Taught Us: Skills, Examiner Advice and Common Errors

Key Skills to Focus On

• Stoichiometry with gases and solutions: Converting units (m³ to L), finding the limiting reagent and allowing for dilution and mole ratios.
• Faraday's laws: Linking mass, moles of electrons, charge and current.
• Equilibrium calculations: Using an ICE table together with the equilibrium expression.
• Spectroscopy: Linking each piece of IR, mass spectrometry and NMR data to a specific structural feature.
• Extended responses: Structuring an argument around green chemistry principles, supporting evidence, an ethical factor and a conclusion.

Advice to Students From the Examiner's Report

• Answer in the form asked: In Question 3d, many students gave a concentration instead of an amount in mol. In Question 4a.ii, the stem asked for names, but many students gave formulas.
• Include units and positive values: In Question 1b, energy released should be given as a positive value with units (454 kJ), not −454 kJ.
• Thermochemical equations need states: In Question 1a, ΔH = −2220 kJ had to be paired with the correct states at SLC, including liquid water.
• Use an ICE table: The examiners strongly recommend an I.C.E. table for equilibrium questions with initial and final states (Q3d).
• Be specific about stresses: "Increasing the pressure" wasn't enough in Question 3b.ii, because adding an inert gas increases pressure without shifting equilibrium. Answers needed to say how the pressure increased, such as decreasing the volume.
• Use the Data Book: The m³-to-L conversion (Q1d) and the colour of Mn²⁺ (Q6b) were both in the Data Book.
• Don't justify with chemical shifts: In Questions 4d and 4e, chemical shifts couldn't be used to justify structural features. Marks came from peak numbers, splitting patterns and peak area ratios.

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Common Mistakes Made in Section B

#### Fuels and Energy

• Limiting reagent with gases (Q1d): Many students couldn't convert 0.125 m³ to 125 L, then struggled to find the limiting reagent and didn't calculate how much excess reagent remained.
• Energy content (Q1e): The difference between ethanol and propane comes from ethanol already being partially oxidised (it contains a hydroxy group). Explanations based on bond enthalpies weren't accepted.

#### Electrochemistry

• Oxidation numbers (Q2a): Write +3, not 3+, and use correct terminology for electron transfer.
• Electroplating (Q2b): Most students didn't recognise that commercial electroplating needs a constant electrolyte concentration. Cr³⁺ is produced at the anode at the same rate it is used at the cathode.
• Competing reactions (Q2c): H⁺ is a stronger oxidant than Cr³⁺, so too much acid produces hydrogen gas instead of chromium plating. Students often called Cr an oxidant or treated H₂SO₄ as a direct source of H₂.
• Comparing currents (Q2e): Because Cr³⁺ and Rh³⁺ have the same charge, the heavier rhodium needs fewer moles of electrons for the same mass and so a lower current. Comparing voltages was a common misconception.

#### Equilibrium

• Reversible reactions (Q3a): A reversible reaction can proceed in either direction. Defining equilibrium ("rate of forward = rate of reverse") wasn't accepted.
• Reaction quotient (Q3c): Calculate Q, compare it with K (Q > K), then explain that the system shifts to the left to restore K.

#### Organic and Analytical Chemistry

• Substitution reactions (Q4a.i): The equation needed UV light as a condition.
• Boiling points (Q4b.i): Answers needed to compare intermolecular forces, such as carboxylic acids forming more hydrogen bonds or dimers. Discussing the strength of C=O or O–H bonds, or saying amines only have dispersion forces, was incorrect.
• Parent ion (Q4c.ii): All isomers share the same molecular formula, so they all show a parent ion at m/z = 108. "Same molecular mass" wasn't accepted, because the molar mass is 108.5 g mol⁻¹.
• Fragment ions (Q4c.iii): The formula had to show the ³⁷Cl isotope and a single positive charge: [C₃H₆³⁷ClO]⁺.
• ¹H NMR (Q4d): Marks were awarded for linking data to features: three peaks mean three hydrogen environments, singlets mean no neighbouring hydrogens, and a 1:2:6 ratio suggests two equivalent CH₃ groups.
• HPLC (Q5a.i): Run a quinine standard under the same conditions and match its retention time, or "spike" the sample and look for the peak to grow.
• Chirality (Q5c.i): A chiral centre has four different groups, producing differently shaped isomers, and only one has the shape needed to fit the enzyme's active site.

#### Investigation Skills

• Titration end point (Q6b): The end point is the first permanent purple colour from excess permanganate. "Pink" wasn't accepted, because Mn²⁺ (pink) forms throughout the titration.
• Redox titration (Q6e): The most common issue was not allowing for dilution (25 mL aliquot from 500 mL) or the 5:2 mole ratio.
• Evaluating a hypothesis (Q6h): Compare the result from 6f with the 75% predicted in the hypothesis.
• Sources of error (Q6g): Residual water on the leaves would add soluble oxalate, leading to a larger titre.

#### Sustainability and Ethics (Q7b)

The 6-mark extended response rewarded a clear structure:

• two relevant green chemistry principles, each supported by evidence, such as waste prevention (CO₂ vs O₂), energy efficiency (2200 vs 1600 temperature requirements) or atom economy (62.8% vs 69.9%)
• a relevant ethical factor, such as unequal global access to renewable electricity, job losses or demand for rare platinum and iridium
• a conclusion that follows from the evidence.

Conclusion

Students in 2025 were confident with routine calculations and sustainability concepts. The marks that separated students came from electrochemistry reasoning, organic analysis and precise communication.

To improve your score:

• practise multi-step calculations and always check units, mole ratios and dilutions
• learn to justify every structural feature with a specific piece of spectroscopic data
• answer exactly what the question asks (mol or M, name or formula, positive energy values)
• prepare a clear structure for extended sustainability and ethics questions.

For more preparation:

• read how one of our tutors scored a 50 in VCE Chemistry
• see everything you need to know about VCE Chemistry
• check how Chemistry scaled in the 2025 VCE scaling report
• see the VCE exam timetable 2026 for this year's exam dates.

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Source: VCAA, 2025 VCE Chemistry external assessment report.