A student investigated the mass of magnesium oxide produced by the thermal decomposition of magnesium carbonate:
MgCO3(s)→MgO(s)+CO2(g) \text{MgCO}_3(\text{s}) \rightarrow \text{MgO}(\text{s}) + \text{CO}_2(\text{g}) MgCO3(s)→MgO(s)+CO2(g)The table below shows the student's results:
| Mass of magnesium carbonate (g) | Mass of magnesium oxide (g): Trial 1 | Mass of magnesium oxide (g): Trial 2 | Mass of magnesium oxide (g): Trial 3 | Mean mass of magnesium oxide (g) |
|---|---|---|---|---|
| 4.00 | 1.92 | 1.89 | 1.92 | 1.91 |
| 8.00 | 3.84 | 3.81 | 3.84 | 3.83 |
| 12.00 | 3.20 | 5.76 | 5.74 | ZZZ |
| 16.00 | 7.67 | 7.63 | 7.65 | 7.65 |
Identify the anomalous result in the table by stating the mass of magnesium carbonate and the trial number.
Calculate the mean mass ZZZ of magnesium oxide produced from 12.00 g of magnesium carbonate. You should exclude the anomalous result from your calculation.
Use your value of ZZZ to calculate the mass of magnesium oxide produced when 180.0 g of magnesium 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.