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)

Respuesta :

Answer : The value of equilibrium constant [tex]K_p[/tex] for the reaction is, 3.82

Explanation :

First we have to calculate the pressure of phosgene gas.

Using ideal gas equation:

[tex]PV=nRT[/tex]

where,

P = Pressure of phosgene gas = ?

V = Volume of phosgene gas = 1.50 L

n = number of moles phosgene = [tex]3.30\times 10^{-2}mol[/tex]

R = Gas constant = [tex]0.0821L.atm/mol.K[/tex]

T = Temperature of phosgene gas = 800 K

Putting values in above equation, we get:

[tex]P\times 1.50L=3.30\times 10^{-2}mol\times (0.0821L.atm/mol.K)\times 800K[/tex]

[tex]P=1.44atm[/tex]

Now we have to calculate the value of equilibrium constant.

The balanced equilibrium reaction is:

                          [tex]CO(g)+Cl_2(g)\rightleftharpoons COCl_2(g)[/tex]

Initial pressure    0           0             1.44

At eqm.                P           P          (1.44-P)

The expression of equilibrium constant [tex]K_p[/tex] for the reaction will be:

[tex]K_p=\frac{(p_{COCl_2})}{(p_{CO})\times (p_{Cl_2})}[/tex]

As we are given that:

[tex]p_{CO}=0.497atm[/tex]

That means, P = 0.497 atm

[tex]K_p=\frac{(1.44-P)}{(P)\times (P)}[/tex]

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

[tex]K_p=\frac{(1.44-0.497)}{(0.497)\times (0.497)}[/tex]

[tex]K_p=3.82[/tex]

Thus, the value of equilibrium constant [tex]K_p[/tex] for the reaction is, 3.82