Answers section
Questions 5.4.1(b)
Complete the following table to describe, in words and chemical equations, the burning of hydrogen sulphide in air.
| Condition | Observations when hydrogen sulphide is burning in oxygen (or air) | Equation for the reaction |
| Limited supply of oxygen | ||
| Excess oxygen |
Answers to Questions 5.4.1(b) 
| Condition | Observations when hydrogen sulphide is burning in oxygen (or air) | Equation for the reaction |
| Limited supply of oxygen | The gas burns with a pale blue flame. A fine yellow solid deposits on a cooler surface, together with colourless droplets. | 2H2S(g) + O2(g) → 2H2O(g) + S(s) |
| Excess oxygen | The gas burns with a blue flame. A colouless gas that turns blue litmus red then rapidly bleaches it is produced. | 2H2S(g) + 3O2(g) → 2H2O(g) + 2SO2(s) |