Dry hydrogen when passed over heated metals like Na, K and Ca, reacts to give their corresponding hydrides.
- Most of the metals do not react with hydrogen. Only a few reactive metals react with hydrogen to form metal hydrides. For example: When hydrogen gas is passed over heated sodium, then sodium hydride is formed.
- Non-metals react with hydrogen to form covalent hydrides. For example, Sulphur combines with hydrogen to form hydrogen sulphide.
- Dry Hydrogen is one of the most active agents for reducing the oxides of many metals in the furnace.