Question

Write equations for the reactions of
(i) iron with steam
(ii) calcium and potassium with water

Answer 1

3Fe + 4H2O -> Fe3O4 +4H2
Ca +2H2O -> Ca(OH)2 + H2
2K + 2H2O -> 2K(OH) +H2

Answer 2

Answer:

(i) Iron reacts with steam to form a magnetic oxide of Fe with the liberation of H2.

3Fe(s) + 4H2O(g) → Fe3O4(s) + 4H2(g)

(ii) Calcium reacts with water to form calcium hydroxide and hydrogen.

Ca(s) + 2H2O(I) → Ca(OH)2(aq) + H2(g)

Potassium reacts with cold water violently immediately with evolution of H2 which catches fire.

2K(s) + 2H2O(I) → 2KOH(aq) + 2H2(g)