A student investigated the mass of sodium carbonate produced by the thermal decomposition of sodium hydrogencarbonate:
2NaHCO3(s)→Na2CO3(s)+H2O(g)+CO2(g) 2\text{NaHCO}_3(\text{s}) \rightarrow \text{Na}_2\text{CO}_3(\text{s}) + \text{H}_2\text{O}(\text{g}) + \text{CO}_2(\text{g}) 2NaHCO3(s)→Na2CO3(s)+H2O(g)+CO2(g)The table below shows the student's results:
| Mass of sodium hydrogencarbonate (g) | Mass of sodium carbonate (g): Trial 1 | Mass of sodium carbonate (g): Trial 2 | Mass of sodium carbonate (g): Trial 3 | Mean mass of sodium carbonate (g) |
|---|---|---|---|---|
| 4.00 | 2.50 | 2.54 | 2.52 | 2.52 |
| 8.00 | 5.02 | 5.08 | 5.05 | 5.05 |
| 12.00 | 7.55 | 7.61 | 4.20 | ZZZ |
| 16.00 | 10.06 | 10.12 | 10.09 | 10.09 |
Identify the anomalous result in the table by stating the mass of sodium hydrogencarbonate and the trial number.
Calculate the mean mass ZZZ of sodium carbonate produced from 12.00 g of sodium hydrogencarbonate. You should exclude the anomalous result from your calculation.
Use your value of ZZZ to calculate the mass of sodium carbonate produced when 150.0 g of sodium hydrogencarbonate 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.