Question

Write a balanced equation for when zinc metal reacts with an aqueous hydroxide ions.

A gas and a complex ion is formed

Answer 1

Answer and explanation;

• Zinc metal reacts with strong bases forming hydrogen gas:

Zn(s) + 2 OH−(aq) → Zn(OH)2(s) + H2(g)

• Zn2+ is precipitated by hydroxide ions as Zn(OH)2 (white amorphous precipitate)

Zn2+(aq) + 2 OH−(aq) ⇄ Zn(OH)2 (s)

• By acid excess hydroxide ions, the precipitate is dissolved.

Zn(OH)2(s) + 2 H+(aq) ⇄ Zn2+(aq) + 2 H2O(l)

Zn(OH)2(s) + 2 OH−(aq) ⇄ [Zn(OH)4]2−(aq)

• [Zn(OH)4]2−(aq) is the complex ion