Chapter 13, Problem 13.61AQAP

Consider the reaction: (10.3)

${\text{2NH}}_{\text{3}}\left(\text{g}\right)\rightleftharpoons {\text{ N}}_{\text{2}}\left(\text{g}\right)+{\text{3H}}_2\left(\text{g}\right)$

a Write the equilibrium constant expression
b Whet is the numerical value of ${\text{K}}_{\text{c}}$ for the reaction if the concentrations at equilibrium are $0.\text{2}0{\text{ M NH}}_{\text{3}}$ , $0.\text{3}0{\text{ M N}}_{\text{2}}$ , and $0.\text{5}0{\text{ M H}}_{\text{2}}$ ?