Question

Given the following information:

hydrocyanic acid	HCN	Ka = 4.0×10-10
hypochlorous acid	HClO	Ka = 3.5×10-8

(1) Write the net ionic equation for the reaction that occurs when equal volumes of 0.292 Maqueous hydrocyanic acid and sodium hypochlorite are mixed. It is not necessary to include states such as (aq) or (s).

(2) At equilibrium will the reactants or products be favored?

(3) Will the pH of the resulting solution be less than seven, greater than seven or equal to seven?

Answer 1

(1) net ionic equation : HCN (aq) + ClO^- (aq) CN^- (aq) + HClO (aq)

(2) At equilibrium reactants will be favored.

(3) pH of the resulting solution will be greater than seven.

Explanation

It is given that hypochlorous acid HClO is stronger than hydrocyanic acid HCN (because K_a for HClO > K_a for HCN).

This means conjugate base of hypochlorous acid, chlorite ClO^- will be a weaker base than conjugate base of hydrocyanic acid, CN^-.

Therefore, CN^- will be the stronger base and push the reaction towards reactant side.