Chemical Equilibrium questions (PLS ANSWER URGENT)

Question

Phosgene gas, COCl2, dissociates to form carbon monoxide and chlorine.

COCl2(g) ↔ CO(g) + Cl2 (g)

A 0.80 mol sample of COCl2 (g) dissociates in a 1.0 dm3

flask at 420K. At equilibrium,

22.5% of COCl2 (g) has dissociated.

(a) Calculate the equilibrium constant, Kc and the value of Kp.(

(b) What is the total pressure in the flask at equilibrium?

Answer 1

COCl2(g) ↔ CO(g) + Cl2 (g) is a balanced equation.

If you begin with 0.8 moles phosgene and 22.5 % dissociated, you would have at equilibrium 0.8 x 0.225 = 0.18 moles of CO and Cl2 and 0.8 -0.18 = 0.62 moles of phosgene.

Kc = [CO] [Cl2] / [COCl2] = 0.18/1L x 0.18 /1L / 0.62/1L 1 dm^3 = 1 L

Kc = 0.052

To get Kp we have to calculate the partial pressures.

Kp = P_co x P_Cl2 / P_COCl2 , but each partial pressure is the pressure the gas would occupy if it were the only gas in the volume. Each partial pressure = n_{moles gas} x R x T /V

Kp = n_CORT/V x n_Cl2RT/V / n_COCl RT/V

Kp = 0.18² / 0.62 x RT/V = 0.052 x 0.082 x 420 / 1L = 0.00040