A student heats iron wool in an open porcelain dish. The iron reacts with oxygen from the air.
4Fe+3O2→2Fe2O3 4\mathrm{Fe} + 3\mathrm{O_2} \rightarrow 2\mathrm{Fe_2O_3} 4Fe+3O2→2Fe2O3The student cools and weighs the dish and its contents after each heating.
| Stage | Mass / g |
|---|---|
| Empty dish | 18.42 |
| Dish and iron before heating | 24.00 |
| Dish and contents after first heating | 26.34 |
| Dish and contents after second heating | 26.34 |
Relative atomic mass (ArA_rAr): O = 16.0 Fe = 55.8
Calculate the expected mass of the dish and its contents if all the iron reacts and no solid is lost.
Give your answer to two decimal places.
Evaluate the claim: ‘All the iron reacted and no solid was lost from the dish.’
Use the results and your answer to part (a).
134 exam-style questions on OCR GCSE Chemistry 3.1 Introducing chemical reactions, covering 3.1.1 Writing formulae and balanced chemical equations, 3.1.2 Formulae of compounds from ions, and state symbols, 3.1.3 Conservation of mass and observed changes in mass, 3.1.4 Half equations and balanced ionic equations, 3.1.5 The mole and the Avogadro constant, and 3.1.6 Stoichiometry, limiting reactants and reacting masses. Each one has a worked solution and a mark scheme showing where the marks go.