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3.5 Use of amount of substance in relation to volumes of gases

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Question 14

A student heated potassium chlorate with a catalyst in a boiling tube connected to a gas syringe. The potassium chlorate decomposed completely.

2KClO3→2KCl+3O22\text{KClO}_3 \rightarrow 2\text{KCl} + 3\text{O}_22KClO3​→2KCl+3O2​

The apparatus was left to cool to room temperature before the final reading was taken. All volumes were measured at room temperature and pressure.

InformationValue
Gas syringe reading before heating4 cm3
Gas syringe reading after cooling76 cm3
Relative formula mass of potassium chlorate122.5
Volume occupied by one mole of any gas at room temperature and pressure24 dm3

Calculate the mass, in g, of potassium chlorate that decomposed.

[4]
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3.5 Use of amount of substance in relation to volumes of gases Questions

  1. GCSE
  2. /Chemistry
  3. /3.5 Use of amount of substance in relation to volumes of gases

100 exam-style questions on AQA GCSE Chemistry 3.5 Use of amount of substance in relation to volumes of gases, covering 3.5.1 Volumes of gases. Each one has a worked solution and a mark scheme showing where the marks go.

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