what is the difference between Kp and Kc?
Kp is used for reactions involving gases, and the equilibrium constant is expressed in terms of the partial pressures of the gases. Whereas, Kc is used as a general constant, and the concentrations (in moles/liter) are used in calculating its value.
Kc is the ratio of products� concentration over reactants� concentration and Kp is the ratio of products� partial pressures and reactants� partial pressures.
Kp = Kc X (R T)^( ?n)