The reactivity series is based on the reaction of metals with water or dilute hydrochloric acid.
- A metal high up in the reactivity series:
- reacts vigorously with chemicals eg water
- readily gives up electrons to form positive ions
- corrode easily
- A metal low down in the reactivity series;
- reacts less with chemicals
- does not readily gives up electrons to form positive ions
- does not corrode easily
- Metals below hydrogen in the series do not react with acids to produce hydrogen gas.
Order of reactivity series
- Potassium
- Sodium
- Calcium
- Magnesium
- Aluminum
- Zinc
- Iron
- Lead
- Hydrogen
- Copper
- Silver
- Gold
| Reactivity series | Rxn with H2O / steam | Rxn with dil HCl |
|---|---|---|
| Potassium Sodium |
React violently with cold water | explosive reaction |
| Calcium | reacts quickly with cold water | very vigorous rxn |
| Magnesium | very slowly with cold water/ rapidly with steam to form oxide | very vigorous rxn |
| Zinc Iron |
React when heated in steam .do not react with cold water | Reacts |
| Hydrogen | ||
| Copper | Does not react with steam/water | metals below H2 do not react with dil acids |
Reaction of K(s), Na(s) and Ca(s) with cold water
- Metal + water → Metal hydroxide + Hydrogen
Reaction of Mg(s), Zn(s) and Fe(s) with steam
- Metal + Water → Metal Oxide + Hydrogen
- iron does not react with water
- copper and gold hve no reations with water and steam
Reaction of K(s), Na(s), Ca(s), Mg(s), Zn(s), and Fe(s) with dilute hydrochloric acid
- Metal + Acid → Metal chloride + Hydrogen
- lead reacts with warm HCl slowly
- copper and gold have no reaction
Displacement reactions
it is the displacement of ions of metal from compounds of metal lower in reactivity series by metals higher in reactivity series.
- when magnesium powder and copper (II) oxide powder is heated there is a vigorous exothermic reaction. The magnesium takes oxygen from copper (II) oxide to from magnesium oxide and copper metal.
- Mg(s) + CuO(s) → MgO(s) + Cu(s)
- Hydrogen can take oxygen from metallic oxides, producing the metal and water
- PbO (s) + H2(g) &→ Pb(s) + H2O(l)
- Carbon can take up oxygen from the oxide of metals which are not too high in the reactivity series.
- 2CuO(s) + C(s) → 2Cu(s) + CO2(g)
Uses of reactivity series
- The thermite processes
- The sacrificial protection of iron
- Galvanizing
- Making cells (batteries)