Contents
Independent final check
Explain without the key
determine / calculate / explain
Final check
Calcium granules react with water, and the hydrogen is collected in a gas syringe. The table shows the results. (a) Determine the total volume of hydrogen made. (b) Calculate the average rate over the first 10 s. (c) Determine the time at which the reaction stopped. Explain how you can tell.
determine: find the answer from the information given. calculate: work out the answer from the data. explain: give reasons and connect them to evidence.
| Time / s | 0 | 10 | 20 | 30 | 40 | 50 | 60 | 70 |
|---|---|---|---|---|---|---|---|---|
| Volume of hydrogen / cm³ | 0 | 24 | 40 | 50 | 55 | 57 | 57 | 57 |
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Scope and sources
Cambridge IGCSE Chemistry 0620 · 2026–2028 v2 · Original learning materials.
Rate of reaction (6.2 Core 1–4, Supplement 5–8): the effect of concentration, gas pressure, surface area, temperature and a catalyst, catalysts and enzymes, practical methods for following a rate and interpreting its data, collision theory and activation energy. Moles and gas volumes are in an earlier module; reversible reactions and equilibrium in 6.3.
Apparatus, amounts and times in the experiment are illustrative. Real practical work follows a teacher-approved safety method.
Official Cambridge syllabus