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HKDSE Chemistry Paper 2 Mock (2027): Industrial, Materials and Analytical Chemistry with Answers
TUTORZONE ORIGINAL MOCK PAPER · HKDSE CHEMISTRY PAPER 2 (ELECTIVES)
Written to the HKEAA 2027 framework: Paper 2 covers the Elective Part, 20% of the subject mark in 1 hour of structured questions, and candidates answer the questions on two electives. This paper prints all three electives – Industrial, Materials and Analytical Chemistry – 4 questions and 20 marks each, 12 questions in all, with worked answers and mark allocation.
What is in HKDSE Chemistry Paper 2?
Direct answer: Paper 2 covers the Elective Part: 20% of the subject in 1 hour of structured questions, and candidates answer two of the three electives – Industrial, Materials and Analytical Chemistry. Paper 1 covers the Compulsory Part at 60% (2 hours 30 minutes) and SBA is 20%.
Assessment at a glance (2027)
| Component | Content | Weighting | Duration |
|---|---|---|---|
| Elective XIII: Industrial Chemistry | Importance of industrial processes, rate equations, activation energy, catalysis and green chemistry; 4 questions, 20 marks in this paper | 20% | 1 hour (whole paper) |
| Elective XIV: Materials Chemistry | Natural and synthetic polymers, metals and alloys, ceramics and glasses, nanomaterials and liquid crystals; 4 questions, 20 marks in this paper | 20% | 1 hour (whole paper) |
| Elective XV: Analytical Chemistry | Detecting species, separation and purification, quantitative analysis such as titration, and instrumental methods including colorimetry and spectra; 4 questions, 20 marks in this paper | 20% | 1 hour (whole paper) |
| The rest of the subject (for reference) | Paper 1 covers the Compulsory Part at 60% in 2 hours 30 minutes (Section A multiple-choice 18% of the subject mark, Section B 42%, all compulsory); SBA is 20% | 60% + 20% | 2 h 30 min |
Paper 2 gives you 60 minutes for 40 marks (two electives), about 1.5 minutes per mark: aim at about 25 minutes per elective and keep 10 minutes to check. In Analytical Chemistry always show the moles and the unit; in Materials Chemistry answer explanations as structure, property, then use; in Industrial Chemistry write the expression before substituting numbers rather than leaping to an answer.
How this paper was built
This is a TutorZone original mock paper: every question, answer and mark allocation is our own, not an HKEAA past paper or marking reference. Only the framework figures (Paper 2 at 20%, 1 hour, structured questions, two of three electives) come from the HKEAA 2027 assessment framework.
HKEAA publishes neither a fixed question count for Paper 2 nor a per-elective mark split, so this paper sets its own: 4 questions and 20 marks per elective, and candidates answer two electives (40 marks in total). Every numeric answer was recomputed programmatically.
Pacing
| Section | Marks | Suggested time | What to do first |
|---|---|---|---|
| Elective XIII: Industrial Chemistry | 20% | about 25 min | Get the orders from the rate ratios first, then work out k and its unit |
| Elective XIV: Materials Chemistry | 20% | about 25 min | Answer every explanation as structure, then property, then use |
| Elective XV: Analytical Chemistry | 20% | about 25 min | Titration: write n = cV with V in dm³, and note the mole ratio beside it |
| The rest of the subject (for reference) | 60% + 20% | outside Paper 2 | Paper 2 is electives only – do not mix it with Paper 1 compulsory content |
How should the 60 minutes be split?
Direct answer: 40 marks across two electives – about 25 minutes per elective and 10 minutes to check. Start with the elective you know best, write the expression before substituting, answer explanations as structure, property, then use, and spend the last 10 minutes on units, mole ratios and blanks.
Elective XIII: Industrial Chemistry (4 questions, 20 marks)
Aim at 25 minutes. Attempt only the two electives you studied; all three are printed here so you can compare and self-study.
Question 1 (5 marks)
For the reaction A + B → C: Experiment 1 has [A] = 0.10 mol dm⁻³ and [B] = 0.10 mol dm⁻³ with an initial rate of 2.0 × 10⁻³ mol dm⁻³ s⁻¹; Experiment 2 has [A] = 0.20 and [B] = 0.10 with a rate of 4.0 × 10⁻³; Experiment 3 has [A] = 0.10 and [B] = 0.20 with a rate of 8.0 × 10⁻³. (a) Find the order with respect to A and to B; (b) write the rate equation; (c) find the rate constant k and its unit.
Question 2 (5 marks)
Industrially, ammonia is oxidised to nitrogen monoxide: 4NH₃ + 5O₂ → 4NO + 6H₂O. (a) Find the atom economy of this reaction as a percentage (one decimal place), showing your working; (b) in the ammonia synthesis, 10 mol of nitrogen reacts with excess hydrogen and 14 mol of ammonia is obtained. Find the percentage yield.
Question 3 (5 marks)
An industrial reaction has an activation energy of 180 kJ mol⁻¹ without a catalyst and 90 kJ mol⁻¹ with one. (a) Explain how a catalyst raises the rate; (b) state two further advantages of using a catalyst in industry; (c) does a catalyst raise the equilibrium yield of an exothermic reaction? Explain.
Question 4 (5 marks)
(a) Name the reaction type and the repeat unit when ethene is converted into poly(ethene); (b) a sample of poly(ethene) has a molar mass of 1.4 × 10⁵ g mol⁻¹ and the repeat unit is 28 g mol⁻¹ – find the degree of polymerisation; (c) explain why synthetic detergents work better than soap in hard water.
Elective XIV: Materials Chemistry (4 questions, 20 marks)
Aim at 25 minutes. Explanation marks need the structure or the chemistry; a bare conclusion earns nothing.
Question 1 (5 marks)
(a) Explain why an alloy is usually harder than the pure metal it is made from; (b) a 400 g bronze sample contains 48 g of tin – find the mass percentage of tin and of copper in the sample; (c) state the main components of brass and of stainless steel.
Question 2 (5 marks)
(a) Which class of material do ceramics belong to, and what is their structure like? (b) Name three types of glass and give one use for each; (c) explain why ceramics break easily.
Question 3 (5 marks)
(a) The repeat unit of nylon 6,6 has a molar mass of 226 g mol⁻¹. A sample has a molar mass of 2.26 × 10⁴ g mol⁻¹ – find the degree of polymerisation; (b) give one example of a composite material and name its two components; (c) explain why a composite can outperform a single material.
Question 4 (5 marks)
(a) Define a nanomaterial and explain why its properties differ from those of the bulk material; (b) a carbon nanotube is 20 nm across and 1 μm long – find its aspect ratio; (c) explain how liquid crystals are used in an LCD.
Elective XV: Analytical Chemistry (4 questions, 20 marks)
Aim at 25 minutes. Titration and colorimetry answers need units; identification questions need the observation, not just the conclusion.
Question 1 (5 marks)
(a) Sodium hydroxide solution is added to copper(II) chloride solution and to iron(III) chloride solution – state what is seen in each case; (b) how would you show that a solid contains carbonate ions? (c) describe the flame test for potassium ions and the technique it needs.
Question 2 (5 marks)
(a) Name the method used to separate each mixture: (i) ethanol and water; (ii) sand and salt solution. (b) Explain the principle behind solvent extraction. (c) In chromatography a component moves 4.8 cm from the start line while the solvent front moves 8.0 cm – find its Rf value.
Question 3 (5 marks)
25.0 cm³ of sodium hydroxide solution is titrated with 0.100 mol dm⁻³ hydrochloric acid, of which 22.5 cm³ is used on average. (a) Write the ionic equation; (b) find the moles of acid used; (c) find the concentration of the sodium hydroxide; (d) if the burette had not been rinsed with the standard acid, would the concentration found be too high or too low? Explain.
Question 4 (5 marks)
(a) In a colorimetric test a 2.0 mg dm⁻³ standard gives an absorbance of 0.24 and an unknown sample gives 0.36 in the same cell at the same wavelength. Assuming Beer’s law, find the concentration of the sample. (b) The mass spectrum of a compound shows peaks at m/z = 94 and 96 with intensities in the ratio 3:1 – which halogen does it contain, and how many atoms? (c) Which functional group is shown by a strong absorption at 1 700 cm⁻¹ in an infrared spectrum?
Where are the answers, and do they show the steps?
Direct answer: each elective is followed by its own answer section giving the expression, the value, the unit and the marks per step (the titration question: 1 mark for the ionic equation, 1 for the moles, 1 for the concentration, 2 for the error analysis), plus the commonest way to lose each step.
Elective XIII answers and mark allocation
Question 1
(a) From Experiments 1 to 2 [A] doubles with [B] fixed and the rate doubles, so A is first order (1 mark); from 1 to 3 [B] doubles with [A] fixed and the rate rises four-fold, so B is second order (1 mark). (b) rate = k[A][B]² (1 mark). (c) k = rate ÷ ([A][B]²) = 2.0 × 10⁻³ ÷ (0.10 × 0.10²) = 2.0 mol⁻² dm⁶ s⁻¹ (2 marks).
Question 2
(a) Atom economy = total molar mass of the desired product ÷ total molar mass of all reactants × 100% = (4 × 30) ÷ (4 × 17 + 5 × 32) × 100% = 120 ÷ 228 × 100% = 52.6% (3 marks). (b) Theoretical yield = 10 × 2 = 20 mol, so the percentage yield = 14 ÷ 20 × 100% = 70% (2 marks).
Question 3
(a) The catalyst provides an alternative route with a lower activation energy (1 mark), so a larger fraction of collisions has energy at or above the activation energy, more collisions are effective and the rate rises (1 mark). (b) It allows operation at a lower temperature, saving energy and reducing by-products; it can raise selectivity and cut waste and separation costs (2 marks, one each). (c) No (1 mark): it speeds up the forward and reverse reactions equally, shortening the time to reach equilibrium without changing its position or the equilibrium constant.
Question 4
(a) Addition polymerisation (1 mark) with the repeat unit —CH₂—CH₂— (1 mark). (b) Degree of polymerisation = 1.4 × 10⁵ ÷ 28 = 5 000 (2 marks). (c) The carboxylate ions in soap form insoluble precipitates (scum) with the calcium and magnesium ions in hard water and stop cleaning; the sulphonate salts in a synthetic detergent stay soluble, so they lather and clean as usual (1 mark).
Elective XIV answers and mark allocation
Question 1
(a) Atoms of different sizes are packed into the lattice, so layers of metal atoms can no longer slide over one another easily, making the alloy harder and stronger (2 marks). (b) Tin = 48 ÷ 400 × 100% = 12%; copper = 100% − 12% = 88% (2 marks). (c) Brass is copper with zinc; stainless steel is iron with chromium (usually with nickel too) (1 mark).
Question 2
(a) Inorganic non-metallic materials (1 mark) built as a giant network of ionic and covalent bonds (1 mark). (b) Soda-lime glass (windows, bottles), borosilicate glass (heat-resistant ware such as Pyrex) and lead glass (lenses, crystal glass) (2 marks). (c) There are no layers that can slide, and ionic and covalent bonds cannot glide the way metallic bonds do, so the energy has nowhere to go and the material is brittle (1 mark).
Question 3
(a) Degree of polymerisation = 2.26 × 10⁴ ÷ 226 = 100 (2 marks). (b) Fibreglass (1 mark): glass fibres (the reinforcement) in a polymer matrix (1 mark). (c) The matrix binds, protects and transfers stress while the reinforcement carries the load, so the pair is light, strong and tough at the same time – a combination no single material gives (1 mark).
Question 4
(a) A material with at least one dimension below 100 nm (1 mark); at that scale the surface-area-to-volume ratio and the share of surface atoms rise sharply and quantum effects appear, so the properties differ from the bulk (1 mark). (b) Aspect ratio = 1 000 nm ÷ 20 nm = 50 (2 marks). (c) Liquid-crystal molecules have orientational order but no positional order, and an applied electric field reorients them, changing the polarisation of the light passing through; with polarising filters that switches each pixel on or off (1 mark).
Elective XV answers and mark allocation
Question 1
(a) Copper(II) gives a pale blue precipitate of copper(II) hydroxide (1 mark); iron(III) gives a reddish-brown precipitate of iron(III) hydroxide (1 mark). (b) Add dilute acid: a colourless gas that turns limewater milky confirms carbonate ions (1 mark). (c) Potassium gives a lilac flame (1 mark); sodium’s yellow masks it, so the flame must be viewed through cobalt blue glass (1 mark).
Question 2
(a) (i) Fractional distillation (1 mark); (ii) filter off the sand, then evaporate or crystallise to recover the salt (1 mark). (b) The solute has different solubilities in two immiscible solvents, so the one with the larger partition coefficient extracts more of it into the organic layer, and a separating funnel divides the layers (2 marks). (c) Rf = 4.8 ÷ 8.0 = 0.60 (1 mark).
Question 3
(a) H⁺ + OH⁻ → H₂O (1 mark). (b) n = cV = 0.100 × 22.5 ÷ 1 000 = 2.25 × 10⁻³ mol (1 mark). (c) The ratio is 1:1, so c = 2.25 × 10⁻³ ÷ 0.0250 = 0.0900 mol dm⁻³ (1 mark). (d) Too high (1 mark): water left in the burette dilutes the standard acid, so a larger volume is needed to reach the end point, the moles substituted are too large and the concentration comes out too high (1 mark).
Question 4
(a) Absorbance is proportional to concentration: 0.24 ÷ 2.0 = 0.12 per mg dm⁻³, so the unknown is 0.36 ÷ 0.12 = 3.0 mg dm⁻³ (2 marks). (b) ³⁵Cl and ³⁷Cl occur in a natural abundance ratio of about 3:1 and the peaks are two mass units apart, so the compound holds one chlorine atom (2 marks). (c) A carbonyl group (C=O) (1 mark).
Where are Paper 2 marks most easily lost?
Direct answer: four places – reading the order off the equation coefficients, confusing atom economy with yield, leaving cm³ unconverted or getting the mole ratio wrong in a titration, and explanations that stop at the conclusion. Another classic is answering an elective question with Paper 1 compulsory content, which scores nothing.
Where these marks are usually lost
| Mistake | What it looks like | What it costs | Instead |
|---|---|---|---|
| Treating the order as the equation coefficients | Seeing A + B → C and writing first order for both | Orders come only from experiment, so copying coefficients loses the marks | Compare the concentration ratio with the rate ratio between two runs |
| Mixing up atom economy and yield | Using the actual mass to find atom economy | They measure different things and the marks follow the definition | Atom economy uses the equation only; yield compares actual with theoretical |
| Skipping the unit conversion in titration | Writing c = 0.1 × 22.5 ÷ 25 | cm³ left unconverted and a wrong mole ratio throw the answer off by a factor of ten | Write n = cV with V in dm³, then fix the mole ratio from the equation |
| Explanations that stop at the conclusion | Writing that an alloy is harder or a ceramic is brittle | Explanation marks need reason then consequence; the conclusion alone earns nothing | Every sentence needs its structure or chemistry |
How to use this paper
First sit: pick the two electives you study, close every reference and do the 40 marks in the full 60 minutes.
Mark it: split your losses into conceptual and arithmetic; for arithmetic, rewrite the expression and the unit.
Second sit: redo it three to seven days later aiming for a complete cause-and-effect chain in explanations and a unit on every calculation step.
What should I do after this paper?
Direct answer: sort your losses into conceptual and arithmetic; drill by elective (rate equations and atom economy for Industrial, structure and properties for Materials, titration and instrumental methods for Analytical); then redo the paper in three to seven days and use the Paper 1 mock to keep the compulsory-part rhythm.
FAQ
What is in Paper 2 and how much is it worth?
The Elective Part: 20% of the subject mark in 1 hour, all structured questions, answering two electives. The three electives are Industrial, Materials and Analytical Chemistry. Paper 1 covers the Compulsory Part at 60% and SBA is 20%.
Is this an HKEAA paper?
No. The questions, answers and mark allocation are TutorZone originals – not past papers and not an official marking scheme. Only the framework figures come from the HKEAA 2027 assessment framework.
How many questions are there?
HKEAA publishes no fixed count for Paper 2. This paper sets its own: 4 questions and 20 marks per elective, 12 questions across three electives, of which candidates answer two (8 questions in practice).
Official references
| Resource | What to check |
|---|---|
| HKEAA 2027 HKDSE Chemistry Assessment Framework | Confirm Paper 2’s 20% and 1 hour, and Paper 1’s 60% with the 18/42 split |
| https://www.tutorzone.com.hk/en-dse-chemistry-paper-2-electives-drill-guide/ | Paper 2 electives drilling guide: structured-question technique in one hour |
| https://www.tutorzone.com.hk/en-dse-chemistry-paper-1-mock-2027/ | Paper 1 original mock: 20 MC and 6 long questions |
| https://www.tutorzone.com.hk/en-dse-chemistry-past-paper-drill-guide/ | The full chemistry drilling guide: compulsory against elective revision |
Related: practice area · Paper 2 electives guide · Chemistry Paper 1 mock
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