How to answer QCE Chemistry short response questions

Calculations need every step and a unit; written answers follow the cognitive verb: describe gives features, explain adds cause and effect, and evaluate ends with a judgement.

Answers	Single words, sentences or paragraphs, and calculations
Often on	Unseen graphs, tables or diagrams
Provided	The formula and data book

Write to the question

For a calculation, write each step with its formula, carry the units and give the answer to sensible significant figures.
For explain, give the point, tie it to the substance, conditions or data in the question, then say what it causes.
For evaluate, weigh a strength and a limitation, then give a judgement and its reason.

Use the stimulus

Quote the numbers, the substances or the result in the question. An answer that could be written without reading the stimulus is rarely a full-marks answer.

Try 2 questions

Question 1

The graph shows the titration of 20.00 mL of a weak monoprotic acid with 0.100 mol L⁻¹ sodium hydroxide. The pH is 2.85 at the start, 4.80 after 12.50 mL has been added, and 8.77 at the equivalence point, 25.00 mL. What is Ka for the acid?

Question 2

A student electrolyses a solution of a metal sulfate, MSO₄, which contains M²⁺ ions, and plots the mass of metal deposited against the charge passed. Using F = 96 485 C mol⁻¹, which metal is M?

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Questions people ask

How long should a longer answer be?

Long enough to make each point, tie it to the question and develop it. Plan two or three linked points rather than a list.