Answers section
Questions 5.1.4 (d)
- Give two reasons why it is not advisable to react sulphur with hydrogen by lowering burning sulphur into a gas jar containing hydrogen.
- Describe the observations made.
- Sulphur shows a valency of 2 in its compound with hydrogen. State the formula of the compound.
- Write an equation for the reaction between sulphur and hydrogen.
Answers to Questions 5.1.4 (d) 
- Because hydrogen gas is less dense than air, a gas jar containing it is held upside-down; so we cannot lower burning sulphur into the jar. Secondly, it is risky to prepare large quantities of hydrogen gas, since it burns explosively, should it mix with air gas.
- Sulphur burns with a pale blue flame. A colourless gas with a rotten-egg smell is produced.
- H2S
- H2(g) + S(s) = H2S(g)