A2(g) <=> 2A(g)

Consider the dissociation reaction given above taking place in a reaction vessel. This dissociation reaction starts with n0 moles of A2. At equilibrium we have nA moles of the product A. The pressure at equilibrium is P and the temperature is T.

1) Derive an expression for the equilibrium constant KP at temperature T in terms of n0, nA and P.

2) Define the degree of dissociation as a=(of moles of product present at equilibrium) / (of moles of reactant present at the start of the reaction)

Find an expression for ? in terms of KP and P.