A student investigated the rate of reaction between magnesium and hydrochloric acid. The equation for the reaction is: Mg(s)+2HCl(aq)→MgCl2(aq)+H2(g)\text{Mg(s)} + 2\text{HCl(aq)} \rightarrow \text{MgCl}_2\text{(aq)} + \text{H}_2\text{(g)}Mg(s)+2HCl(aq)→MgCl2(aq)+H2(g) The diagram below shows the volume of hydrogen gas collected in an inverted 100 cm3100\text{ cm}^3100 cm3 measuring cylinder after 30 seconds30\text{ seconds}30 seconds and after 90 seconds90\text{ seconds}90 seconds. 
Determine the number of moles of hydrogen collected between 30 seconds30\text{ seconds}30 seconds and 90 seconds90\text{ seconds}90 seconds. The volume of one mole of any gas at room temperature and pressure is 24 dm324\text{ dm}^324 dm3. Give your final answer to two significant figures.
Practise AQA GCSE Chemistry Rate of reaction with exam-style questions for Foundation and Higher tier. 46 questions covering Calculating rates of reactions, Factors which affect the rates of chemical reactions, Collision theory and activation energy, and Catalysts, matched to the AQA GCSE Chemistry (8462) specification and written in Paper 1 and Paper 2 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.