Question

derive equillibrium constant for preparation of ammonia​

Answer 1

For the reaction of nitrogen with hydrogen to form ammonia, the balanced chemical equation is

                     N2(g) + 3H2(g) <=====> 2NH3(g)
For the reaction 
The rate of forward reaction       R f = k f [N2] [H2]3 
The rate of reverse reaction Rr = kr [NH3]2
The expression for the equilibrium constant for this reaction is
                                   [NH2]2 
                             Kc= [N2] [H2]3