Write equilibrium constant expressions.

Question

1. Write equilibrium constant expressions for the following reactions in terms of concentration:

(a)   PCl₃(g) + Cl₂(g) PCl₅(g)

K =

(b)   W(s) + 2 H₂O(g) WO₂(s) + 2 H₂(g)

K =

(c)   HN₃(aq) + H₂O() H₃O⁺(aq) + N₃}^-(aq)

K =

Answer 1

To write an equilibrium expression, you place the product of the products (each raised to a power of their coefficient) divided by the product of the reactants (each raised to a power of their coefficient). You DO NOT include solids or liquids when writing Kc expressions.

(a)   PCl3(g) + Cl2(g) <==> PCl5(g)

Kc = [PCl5] / [PCl3][Cl2]

(b) W(s) + 2H2O(g) <==> WO2(s) + 2H2(g)

Kc = [H2]² / [H2O]²

(c) HN₃(aq) + H2O(l) <==> H3O⁺(aq) + N₃^-(aq)

Kc = [H3O⁺][N₃^-] / [HN₃]