Question

For the reaction PC15 =PC13 + Cl2 if initial
pressure is 4 atm and at equilibrium total
pressure becomes 5 atm, value of Kp will be :
(1) 0.33
(2) 1.33
(3) 0.67
(4) 1.67​

Answer 1

Answer:

Explanation:

Given,

$PCl_5\rightleftharpoons PCl_3+Cl_2$

Initial Pressure of PCl_5 = 4 atm.

Total Equilibrium Pressure = 5 atm.

To Find :-

Value of Kp.

Solution :-

$PCl_5\rightleftharpoons PCl_3+Cl_2$

For 'PCl_5' :-

Initial Pressure(I) = 4 atm

Change in Pressure(C) = -x

Equilibrium Pressure(E) = 4 - x

For 'PCl_3' :-

Initial Pressure(I) = 0 atm

Change in Pressure(C) = x

Equilibrium Pressure(E) =  x

For 'Cl_2' :-

Initial Pressure(I) = 0 atm

Change in Pressure(C) = x

Equilibrium Pressure(E) =  x

According to Question :-

4 - x + x + x = 5 atm

4 + x = 5atm

x = 1 atm

$\implies$

4 - x = 4 - 1 = 3atm

x = 1 atm

x = 1 atm

$K_p=\dfrac{[PCl_3][Cl_2]}{[PCl_5]}$

$=\dfrac{1\times 1}{3}$

$=\dfrac{1}{3}$

= 0.33  

Since, option '1' :- 0.33