Question

The active masses of pure solid or liquid phasesare not included in the expression of equilibrium constant as:
a)solid and liquid concentrations are independent of their quantities
b)solids and liquids react very slowly
c)solids and liquids at equilibrium do not interact with gaseous phase

d)the molecules of solids and liquids do not migrate to the gaseous phase

• A. solid and liquid concentrations are independent of their quantities
• B. solids and liquids react very slowly
• C. solids and liquids at equilibrium do not interact with gaseous phase
• D. the molecules of solids and liquids do not migrate to the gaseous phase

Answer 1

The correct option is A

solid and liquid concentrations are independent of their quantities

For the existence of heterogeneous equilibrium, pure solids or pure liquids must be present (even if only present in extremely small quantities) at equilibrium, but their concentrations or partial pressures do not appear in the expression for equilibrium constant.
For example :

$Ag{O}_2$ (s) + $2HN{O}_3$ (aq) ⇌ 2$AgN{O}_3$ (aq) + $H_{2}O$ (l)

Here $K_c$ = $\frac{[AgN{O}_3{]}^2}{[HN{O}_3{]}^2}$