At 250ºC, the equilibrium constant Kp for the reaction PCl5(g) PCl3(g) + Cl2(g) is 1.80. Sufficient PCl5 is put into a reaction vessel to give an initial pressure of 2.74 atm at 250ºC. Calculate the pressure of PCl5 after the system has reached equilibrium

1.2 atm is the pressure of   after the system has reached equilibrium.

Explanation:

Initial pressure of the =2.74 atm

The value of the equilibrium constant =

Initially

2.74 atm      0       0

At equilibrium

(2.74-p)      p         p

The expression of an equilibrium constant can be given as:

Solving for p:

p = 1.50 atm

Pressure of the at equilibrium :

= (2.74-p) atm  = 2.74 - 1.50 atm = 1.2 atm

1.2 atm is the pressure of   after the system has reached equilibrium.

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