A quality-control chemist investigates the formation of sodium sulfide from sodium and sulfur. The substances are pure and react completely. The formulae and measured masses are shown below.
| Substance | Formula | Mass | Molar mass |
|---|---|---|---|
| sodium | Na\text{Na}Na | 9.2 g | 23 g/mol |
| sulfur | S\text{S}S | 6.4 g | 32 g/mol |
| sodium sulfide | Na2S\text{Na}_2\text{S}Na2S | 15.6 g | 78 g/mol |
The unbalanced symbol equation for the reaction is:
Na+S→Na2S\text{Na} + \text{S} \rightarrow \text{Na}_2\text{S}Na+S→Na2S
Calculate the amount, in moles, of each substance. Use your answers to give the balanced symbol equation for the reaction.
131 exam-style questions on AQA GCSE Chemistry 3.2 Use of amount of substance in relation to masses of pure substances, covering 3.2.1 Moles, 3.2.2 Amounts of substances in equations, 3.2.3 Using moles to balance equations, 3.2.4 Limiting reactants, 3.2.5a Concentration of solutions, and 3.2.5b Relating mass, volume and concentration. Each one has a worked solution and a mark scheme showing where the marks go.