Paper 3 · Advanced Practical Skills · past papers worked

Paper 3, past paper by past paper.

Paper 3 is a practical exam: a titration or other quantitative experiment, an energy or rate experiment, and qualitative analysis. Each paper below is rephrased from a real past paper, with a realistic set of readings and observations to work from: answer it part by part, then compare with a worked full-mark answer and the examiner's comments.

May/June 2026, paper 31 · Ion tests, hydrated salt, acid titrationIdentify two salts by tests including ones you plan, find the water in hydrated aluminium sulfate by heating, and titrate diluted sulfuric acid with alkali.
May/June 2026, paper 32 · Displacement enthalpy, copper sulfate hydrate, mixtureFind the enthalpy of zinc displacing copper from a temperature-time graph, find the water in hydrated copper(II) sulfate by heating, and analyse a mixture.
May/June 2026, paper 33 and 37 · Hydrogen volume, substituted-acid titration, ion testsCollect hydrogen from magnesium and an acid, titrate to find the Mr and groups of a halogenated carboxylic acid, and test for unsaturation and for two unknown solutions.
May/June 2026, paper 34 and 38 · Iodate titration, hydrated salt, manganate(VII) testsWork through an iodate(V) and thiosulfate titration, heating a hydrated Group 2 chloride to identify it, and heating potassium manganate(VII) then identifying ions.
May/June 2026, paper 35 · Hydrogen volume, thermometric titration, d-block ionsFind a hydrochloric acid concentration from the hydrogen made with magnesium and from a thermometric titration graph, then test three d-block solutions.
Oct/Nov 2025, paper 31 and 35 and 37 · Ethanedioic acid titration, zinc sulfate hydrateFind the water in hydrated ethanedioic acid by hot manganate(VII) titration and in hydrated zinc sulfate by heating to constant mass, then plan ion tests.
Oct/Nov 2025, paper 33 · Sulfur clock, thiosulfate dissolving, ion testsWork a thiosulfate and acid rate experiment with a rate-volume graph, the enthalpy of solution of hydrated sodium thiosulfate with a Hess plan, and tests on solutions and organic liquids.
Oct/Nov 2025, paper 34 · Hess cycle, impurity titration, copper and iron testsFind the enthalpy of decomposing sodium hydrogencarbonate by Hess's law, titrate out a sodium chloride impurity, and identify a halide, a copper carbonate and iron(II).
Oct/Nov 2025, paper 36 and 38 · Aluminium sulfate heating, iron(II) titration, zincHeat hydrated aluminium sulfate to find its water, titrate iron(II) sulfate with manganate(VII), and identify zinc metal and zinc carbonate.
May/June 2025, paper 31 · Calcium carbonate purity by gas and titrationFind the purity of impure calcium carbonate by collecting carbon dioxide over water and by back titration, then identify copper(II) and two other salts.
May/June 2025, paper 32 · Citric acid titration and Hess's lawShow by titration that citric acid is triprotic, combine two cup experiments by Hess's law, and test copper(II) nitrate and iron(III) chloride.
May/June 2025, paper 33 and 37 · Hydrogen peroxide by titration and thermometryFind the concentration of hydrogen peroxide by manganate(VII) titration and from the temperature rise of its catalysed decomposition, then test three compounds.
May/June 2025, paper 34 and 38 · Iron tablets titration, thermometric neutralisationCheck the iron(II) in supplement tablets by manganate(VII) titration, find a neutralisation point and enthalpy from a two-line graph, and identify compounds and a mixture.
May/June 2025, paper 35 · Group 1 carbonate by gas and titrationIdentify a Group 1 metal from the carbon dioxide its carbonate gives and again by titration, then test three compounds.
Feb/March 2025, paper 33 · Potassium alum formula, manganate(VII) titrationHeat potassium alum to find its anhydrous formula, use an iodine and thiosulfate titration to find the change in oxidation state of manganese, and analyse two salts.
Oct/Nov 2024, paper 31 and 35 · Thermometric titration and carbonate mass lossFind the concentration of sulfuric acid from a thermometric titration graph and from carbon dioxide mass loss, then test three manganese compounds.
Oct/Nov 2024, paper 33 · Hydrated sodium carbonate by mass loss and titrationFind the Mr of hydrated sodium carbonate from carbon dioxide mass loss and a titration, then test copper(II) carbonate and its solution.
Oct/Nov 2024, paper 34 · Iodination rate, Group 2 hydrate, manganate testsWork through a thiosulfate back titration for the rate of iodination of propanone, heating a hydrated Group 2 chloride to identify it, and tests on two salts.
Oct/Nov 2024, paper 36 · Carbonate purity, carbonate mixture, salt mixtureFind the purity of sodium carbonate from collected gas and the make-up of a carbonate mixture by heating, then analyse a mixture of two salts.
May/June 2024, paper 31 · Hess's law, sulfite back titration, ion testsWork a sodium hydroxide and hydrogencarbonate enthalpy pair by Hess's law, an iodine-thiosulfate back titration for the water in hydrated sodium sulfite, and tests on magnesium and two salts.
May/June 2024, paper 32 · Thiosulfate hydration enthalpy, iodate titration, ion testsFind the hydration enthalpy of sodium thiosulfate by Hess's law and the formula of an iodate ion by titration, then identify a nitrate, an iodide and a carbonate.
May/June 2024, paper 33 · Ammonium salts: back titration, purity, analysisWork a back titration for ammonium chloride, the purity of ammonium bromide from its temperature fall, and tests on a zinc carbonate mixture and small organic compounds.
May/June 2024, paper 34 · Basic carbonate by back titration and heatingFind the formula mass of a basic metal carbonate by back titration and by heating to constant mass, then identify ammonium carbonate and pairs of unknowns.
May/June 2024, paper 35 · Clock reaction, ammonium chloride enthalpy, ion testsTime a peroxodisulfate and iodide clock at two concentrations, find the enthalpy of solution of ammonium chloride from a temperature-time graph, and analyse three salts.
Feb/March 2024, paper 33 · Thiosulfate rate, magnesium and copper(II) sulfate enthalpyTime the thiosulfate and acid reaction at five concentrations and graph relative rate, measure the enthalpy change for magnesium and copper(II) sulfate, and identify sulfur anions.
Oct/Nov 2023, paper 31 and 35 · Water in sodium carbonate, two waysFind the water in hydrated sodium carbonate by collecting carbon dioxide over water and by titration, then identify nitrogen ions and manganese compounds.
Oct/Nov 2023, paper 33 · Manganate(VII) titration, magnesium oxide Hess cycleFind a manganate(VII) concentration by iodine-thiosulfate titration, find an enthalpy change for magnesium oxide by Hess's law, then identify zinc carbonate and an iron(III) salt.
Oct/Nov 2023, paper 34 · Iron(III)-iodide clock and enthalpy of solutionInvestigate how iron(III) concentration affects an iodine clock with a curved graph, find an Mr from an enthalpy of solution, then identify zinc carbonate and an acid mixture.
Oct/Nov 2023, paper 36 · Hydrogen peroxide by mass loss and titrationFind the concentration of hydrogen peroxide from oxygen mass loss and a manganate(VII) titration, then identify nitric acid and an iron(II) salt.
May/June 2023, paper 31 · Thiosulfate rate graph, magnesium sulfate dehydrationGraph rate against thiosulfate volume to test direct proportion, find the dehydration enthalpy of hydrated magnesium sulfate by Hess's law, and test two salts.
May/June 2023, paper 32 · Basic carbonate decomposition, carbonate titration, testsFind the Ar of a metal from the mass lost on heating its basic carbonate, identify a Group 1 carbonate by titrating a standard solution, and work through tests on a sulfate and four pairs of unknowns.
May/June 2023, paper 33 · Hydroxylamine redox titration, thiosulfate rateDecide which equation describes hydroxylamine reducing iron(III) by a manganate(VII) titration, find an order for thiosulfate, and identify a mixture and an ammonium salt.
May/June 2023, paper 34 · Thermometric titration, carbonate decomposition, acidsUse a thermometric titration to find an enthalpy of neutralisation and identify a bromo acid, find the Mr of a carbonate from its mass loss on heating, and distinguish three acids.
May/June 2023, paper 35 · Magnesium purity by gas and thermometryWork out the purity of magnesium from the hydrogen collected and again from an extrapolated temperature rise, then test a solid and a solution.
Feb/March 2023, paper 33 · Basic zinc carbonate formula, two waysFind the Mr of basic zinc carbonate by heating to constant mass and by back titration, then identify basic copper(II) carbonate and hydrochloric acid.

How Paper 3 is marked

Manipulation and measurement

Burette readings to 0.05 cm³, concordant titres within 0.10 cm³, balance readings as displayed, temperatures to 0.5 °C or as the scale allows.

Presentation

One results table with headings and units, every reading recorded, and calculations set out step by step with the full value carried through.

Analysis

Moles, concentrations and enthalpy changes to the right number of significant figures, a graph drawn and read the way the question asks, and conclusions from the data.

Observations and deductions

Observations in the wording of the Qualitative Analysis Notes (colour, precipitate, gas and its test) and deductions about the ions or functional groups present.

Habits that save marks

Record every reading: initial and final burette readings, rough and accurate titres, all to two decimal places ending in 0 or 5.
Observations are not deductions: write what you see (a white precipitate, soluble in excess) before naming an ion.
Keep the precision of the data: carry full values through a calculation and round only the final answer.

The questions on this page are rephrased from a Cambridge International past paper for teaching. The readings, figures, wording of the workout and the worked answers are our own; the marking follows the published mark scheme. The original question paper is available from Cambridge.