Question

What is the relation between K_p and K_c? Given one example for which K_p is equal to K_c.

Answer 1

The relation between K_p and K_c is K_p =

K_C (RT)^∆n_g

K_p = equilibrium constant is terms of partial pressure.

K_c = equilibrium constant is terms of concentration.

R = gas constant

T = Temperature.

∆n_g = Difference between the sum of the number of moles of products and the sum of a number of moles of reactants in the gas phase.

When ∆n_g = 0

K_p = K_C(RT)⁰ = K_C i.e., K_p = K_C

Example: \[\ce{H2(g) + l2(g) <=> 2HI(g)}\]

∆n_g = 2 – 2 = 0

∴ K_p = K_C for the synthesis of HI.