Work 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. Paper 3 is done at the bench, so this page gives you a realistic set of readings for each experiment. Process them part by part, see how many of the 40 marks you would earn, then compare with a full-mark worked answer.
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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.
One results table with headings and units, every reading recorded, and calculations set out step by step with the full value carried through.
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 in the wording of the Qualitative Analysis Notes (colour, precipitate, gas and its test) and deductions about the ions or functional groups present.
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.