A student investigated the mass of calcium oxide produced by thermal decomposition of calcium carbonate:
CaCO3(s)→CaO(s)+CO2(g) \text{CaCO}_3(\text{s}) \rightarrow \text{CaO}(\text{s}) + \text{CO}_2(\text{g}) CaCO3(s)→CaO(s)+CO2(g)The table below shows the student's results:
| Mass of calcium carbonate (g) | Mass of calcium oxide (g): Trial 1 | Mass of calcium oxide (g): Trial 2 | Mass of calcium oxide (g): Trial 3 | Mean mass of calcium oxide (g) |
|---|---|---|---|---|
| 5.00 | 2.85 | 2.78 | 2.80 | 2.81 |
| 10.00 | 5.62 | 5.58 | 5.60 | 5.60 |
| 15.00 | 8.38 | 8.42 | 5.10 | YYY |
| 20.00 | 11.24 | 11.18 | 11.21 | 11.21 |
Identify the anomalous result in the table by stating the mass of calcium carbonate and the trial number.
Calculate the mean mass YYY of calcium oxide produced from 15.00 g of calcium carbonate. You should exclude the anomalous result from your calculation.
Use your value of YYY to calculate the mass of calcium oxide produced when 135.0 g of calcium carbonate is heated.
53 exam-style questions on AQA GCSE Chemistry 3.1 Chemical measurements, conservation of mass and the quantitative interpretation of chemical equations, covering 3.1.1 Conservation of mass and balanced chemical equations, 3.1.2 Relative formula mass, 3.1.3 Mass changes when a reactant or product is a gas, and 3.1.4 Chemical measurements. Each one has a worked solution and a mark scheme showing where the marks go.