30 HSC Chemistry practice questions for 2026 (Modules 5-8)

How to use this question bank

HSC Chemistry is a 3-hour exam covering four Year 12 modules. These 30 practice questions span the modules and are modelled on past NESA paper patterns.

Three rules:

1. Show your working. Markers award method marks for correct setup even when the final answer is wrong. Sloppy working that gets the right answer scores lower than careful working that gets a slightly wrong answer.
2. Include units and significant figures. A correct numerical answer in the wrong units loses marks. Round consistently to 3 significant figures unless the question specifies otherwise.
3. Memorise the data sheet. NESA provides a data sheet with constants, formulas, and the periodic table. Knowing it saves time looking up.

Module 5: Equilibrium (1-7)

1. Define dynamic equilibrium. (2 marks)

2. For the reaction $2NO_{2(g)} \rightleftharpoons N_2O_{4(g)}$ with $K_c = 12$ at 100°C, predict the effect of (a) increasing pressure, (b) increasing temperature (given the forward reaction is exothermic). (4 marks)

3. Calculate $K_c$ for the reaction $H_{2(g)} + I_{2(g)} \rightleftharpoons 2HI_{(g)}$ at equilibrium if $[H_2] = 0.10$ M, $[I_2] = 0.10$ M, $[HI] = 0.78$ M. (3 marks)

4. The Haber process produces ammonia: $N_{2(g)} + 3H_{2(g)} \rightleftharpoons 2NH_{3(g)}$, $\Delta H = -92$ kJ/mol. Outline three conditions used industrially AND explain why each is chosen using Le Chatelier's principle. (6 marks)

5. Calculate the solubility (in mol/L) of AgCl in water given $K_{sp} = 1.8 \times 10^{-10}$. (3 marks)

6. A 0.20 M solution of $H_2$ and 0.20 M of $I_2$ in a 1.0 L container at 700K (Kc = 49) reach equilibrium. Use an ICE table to calculate the equilibrium concentration of HI. (5 marks)

7. Explain why adding a catalyst does not shift the position of equilibrium, even though it speeds up the reaction. (3 marks)

Module 6: Acid/Base Reactions (8-15)

8. Calculate the pH of 0.025 M HCl. (2 marks)

9. Calculate the pH of 0.10 M ethanoic acid (Ka = $1.8 \times 10^{-5}$). State any assumptions you make. (5 marks)

10. Identify the conjugate acid-base pairs in the reaction $NH_3 + H_2O \rightleftharpoons NH_4^+ + OH^-$. (3 marks)

11. Sketch a titration curve for the titration of 25.0 mL of 0.10 M ethanoic acid with 0.10 M NaOH. Label the equivalence point and the buffer region. Explain why pH is greater than 7 at the equivalence point. (6 marks)

12. A buffer is prepared from 0.20 M ethanoic acid and 0.20 M sodium ethanoate. Calculate the pH using the Henderson-Hasselbalch equation. (Ka of ethanoic acid = $1.8 \times 10^{-5}$) (4 marks)

13. Explain why phenolphthalein is suitable for a weak-acid / strong-base titration but methyl orange is not. (4 marks)

14. Calculate the volume of 0.15 M NaOH needed to neutralise 25.0 mL of 0.10 M H2SO4. (4 marks)

15. The blood buffer system (carbonic acid / bicarbonate) maintains blood pH at approximately 7.4. Explain how this buffer responds to a rise in CO2 in the blood. (5 marks)

Module 7: Organic Chemistry (16-23)

16. Name the compound CH3-CH(OH)-CH2-CH3 using IUPAC nomenclature. (2 marks)

17. Draw the structural formula of propan-1-ol and propan-2-ol. Explain how they differ. (3 marks)

18. Write a balanced equation for the reaction between ethene and bromine. Classify the reaction type. (3 marks)

19. Predict the major product when 2-methylpropene reacts with HBr. Use Markovnikov's rule. (4 marks)

20. Write a balanced equation for the esterification of ethanoic acid with methanol. Name the ester produced. State the conditions required. (5 marks)

21. Distinguish between addition polymerisation and condensation polymerisation. Use one named example of each. (6 marks)

22. Propose a synthesis route from ethene to ethyl ethanoate, showing each step with the reagents and conditions. (7 marks)

23. Outline the oxidation of an alcohol to a carboxylic acid, including the reagent and one practical observation that distinguishes a primary alcohol from a tertiary alcohol. (5 marks)

Module 8: Applying Chemical Ideas (24-30)

24. Identify the analytical technique most suitable for determining the concentration of a heavy metal (e.g. lead) in a water sample at parts-per-million levels. Justify your choice. (4 marks)

25. A sample is analysed by infrared (IR) spectroscopy. A strong absorption is observed at approximately 1700 cm$^{-1}$. Identify two possible functional groups present. (3 marks)

26. Outline how mass spectrometry can be used to determine the molecular mass of an organic compound. (4 marks)

27. Describe the principle of NMR spectroscopy. What information does it provide about an organic molecule? (4 marks)

28. A solution of an unknown sodium salt is titrated against silver nitrate. Calculate the concentration of chloride ion in the original 100.0 mL solution if 23.5 mL of 0.050 M AgNO3 was required to reach the endpoint. (5 marks)

29. Evaluate the use of one named analytical technique in environmental monitoring (e.g. monitoring air pollution, water quality, soil contamination). (6 marks)

30. A student is given an unknown organic liquid. They perform IR spectroscopy, NMR, and mass spectrometry. The IR shows a broad absorption at 3300 cm$^{-1}$ and a strong absorption at 1700 cm$^{-1}$. The mass spectrum shows M+ = 60. NMR shows three sets of protons. Identify the compound and explain your reasoning. (7 marks)

Marking your own work

For each question:

• 2-3 marks: short answer. Direct response. Include units.
• 4-6 marks: medium response. Show working. Include the relevant equation.
• 7-9 marks: extended response. Multiple paragraphs. Calculate where required, explain mechanism where required, evaluate where required.

A useful self-mark question: did I show every step of my calculation? If yes, you usually scored full method marks even if the final answer was wrong.

Past papers

These practice questions complement past NESA exam papers; they do not replace them. NESA publishes papers at educationstandards.nsw.edu.au. Aim for 6-8 full past papers in Term 4.

Related guides

• HSC Chemistry Modules 5 & 6 (equilibrium and acid-base)
• HSC Chemistry Module 7 (organic chemistry)
• HSC Chemistry hub