1. Reduction of metal oxides with carbon (Displacement + Redox Reactions)
- Metal oxide is reduced, and carbon dioxide is oxidised.
Equation
Metal oxide (s) + carbon (s) → metal (s) + carbon dioxide (g)
Note
The lower the metal is in the reactivity series from carbon → the more readily the reduction of metal oxide will occur
2. Reduction of metal oxides with hydrogen gas
Equation
Metal oxide (s) + hydrogen (g) → metal (s) + steam (g)
Important
Before doing this → it is important that the hydrogen gas is dried → example is by using fused calcium chloride. (Methods for Drying Gasses)
Effect of Reactivity of metals on the ease of reduction of metal oxides
- The more reactive a metal is → the more stable the compounds of a metal to chemical reactions thus lower the tendency for these compounds to undergo chemical reactions ⇒ ^c6fd55
| Metals | Reduction with Hydrogen | Reduction with Carbon |
|---|---|---|
| Potassium Sodium Calcium Magnesium Aluminium | Metal oxides → cannot be reduced by carbon and hydrogen. → oxides of these highly reactive (more reactive) metals → are stable to reduction by hydrogen and carbon | Metal oxides → cannot be reduced by carbon and hydrogen. → oxides of these highly reactive (more reactive) metals → are stable to reduction by hydrogen and carbon |
| Zinc | zinc oxide → cannot be reduced by hydrogen | Oxides of these moderately reactive (less reactive) metals → can be reduced by carbon (C) to form metal and carbon dioxide. Ease of reduction of oxide increases as reactivity of metals decreases |
| Iron Lead Copper Silver Gold Platinum | oxides of these moderately reactive (less reactive) metals can be reduced by hydrogen () to form metal and steam. Ease of reduction of oxide increases as reactivity of metals decreases | Oxides of these moderately reactive (less reactive) metals → can be reduced by carbon (C) to form metal and carbon dioxide. Ease of reduction of oxide increases as reactivity of metals decreases |
Summary
Potassium → Magnesium: not reduced by both hydrogen and carbon Zinc: Carbon but not Hydrogen Iron → Platinum: both carbon and hydrogen, more readily reduced as it goes down the reactivity series