Final answer:
The equilibrium constant expressions for the reactions are K = 1/[PCl3][Cl2] for reaction (a), assuming PCl5(s) concentration is constant, and K = [H2O]^4 / [H2]^4 for reaction (b), excluding solids from the expression.
Step-by-step explanation:
The question asks for the equation for the equilibrium constant (K) for given reactions, requiring the expressions for K and Kp to be written based on the balanced chemical equations.
For reaction (a) PCl3(l) + Cl2(g) → PCl5(s), since PCl5 is a solid, its concentration is constant and thus not included in the expression for K. Therefore, the equilibrium constant expression would be K = 1/[PCl3][Cl2] because the concentrations of liquid and gaseous reactants appear in the denominator as per the convention for equilibrium expressions.
For reaction (b) Fe3O4(s) + 4H2(g) → 3Fe(s) + 4H2O(g), the equilibrium expression is K = [H2O]4 / [H2]4, with the partial pressures of H2O and H2 raised to their respective coefficients in the reaction. Solids are not included in the expression.