Practice Problem 2:

Classify each of the following as either a metathesis or an oxidation-reduction reaction.  Note that mercury usually exists in one of three oxidation states: mercury metal, Hg₂²⁺ ions, or Hg²⁺ ions.

(a) Hg₂²⁺(aq) + 2 OH^-(aq)  Hg₂O(s) + H₂O(l)

(b) Hg₂²⁺(aq)  + Sn²⁺(aq)    2 Hg(l) + Sn⁴⁺(aq)

(c) Hg₂²⁺(aq) + H₂S(aq)    Hg(l) + HgS(s) + 2 H⁺(aq)

(d) Hg₂CrO₄(s) + 2 OH^-(aq)  Hg₂O(s) + CrO₄^2-(aq) + H₂O(l)

Answer

(a) Metathesis

(b) Oxidation-reduction

(c) Oxidation-reduction

(d) Metathesis