Pure phosgene gas (COCl2,), 3.30 x 10-2 mol, was placed in a 1.50-L container. It was heated to 800K, and at equilibrium the pressure of CO was found to be 0.497 atm. Calculate the equilibrium constant, Kp, for the reaction: CO(g) Cl2(g) COCl2(g)

Answer : The value of equilibrium constant for the reaction is, 3.82

Explanation :

First we have to calculate the pressure of phosgene gas.

Using ideal gas equation:

where,

P = Pressure of phosgene gas = ?

V = Volume of phosgene gas = 1.50 L

n = number of moles phosgene =

R = Gas constant =

T = Temperature of phosgene gas = 800 K

Putting values in above equation, we get:

Now we have to calculate the value of equilibrium constant.

The balanced equilibrium reaction is:

Initial pressure    0           0             1.44

At eqm.                P           P          (1.44-P)

The expression of equilibrium constant for the reaction will be:

As we are given that:

That means, P = 0.497 atm

Now put all the values in this expression, we get :

Thus, the value of equilibrium constant for the reaction is, 3.82