group IIA metals

Question 1

Reactions of Group IIA Metals with Water

Answer 1

Reactivity of alkaline earth metals with water ↑s down the group.

1. Beryllium doesn’t react with cold water.
2. Magnesium has very slight reaction with cold water that stops once Mg(OH)2 (almost insoluble) forms barrier over Mg and prevents further reaction.
   Mg (s) + 2H2O (l) → Mg(OH)2 (s) + H2 (g)
3. Calcium, strontium & barium react with cold water with increasing vigour to give metal hydroxide & hydrogen.
   Ba (s) + 2H2O (l) → Ba(OH)2 (aq) + H2 (g)

Question 2

Reactions of Group IIA metals with acids

+ why Be unreactive with acids

Answer 2

Group IIA metals, apart from beryllium, react with aqueous acids with increasing vigour down the group, liberating hydrogen gas.

Beryllium is unreactive w acids as the surface of Be metal is covered with thin layer of oxide which prevents it from reacting with acid.

Powdered Be can react with dilute acids to form hydrogen gas and aquated Be (II) ions.