Question

Predict whether equilibrium constants for the following reactions should be greater than 1 or less 1. than 1: a) Cdlau+CaF b) [Cula) la)+ICuCl] la) CdF2u Calz CuClal lo)+[Cula] (a)

Answer 1

According to Pearson theory of HSAB principle,

Hard acid- Hard base interactions leads to formation of more stable product

Soft acid- Soft base interactions leads to formation of more stable product.

a)             CdI2(s) + CaF2(s) $\rightleftharpoons$ CdF2(s) + CaI2, Keq <1

          In the reactant side, in CdI2 both are soft and in CaF2 both are weak. Therefore, equilibrium will favored in reactant side.

b). [CuI4]^2-(aq) + [CuCl4]^3-(aq) $\rightleftharpoons$    [CuCl]^2-(aq) + [CuI4]^3-(s)   , Keq <1

          In the reactant side, in [CuI4]^2-, Cu2+ is soft and Iodide ion is also soft and in [CuCl4]^3-, Cu+ is borderd line acid and Cl- is hard base. Therefore, equilibrium will favored in reactant side.