Question

For the reaction below, Kp = 29.21 at 800K. Calculate the equilibrium partial pressures of the reactants and products if the initial pressures are Ppcl5 = 0.488atm & Ppcl3 = .4900atm.

PCL5(g) <----> PCL3(g) + Cl2(g)

PCL5: ______ atm

Cl2: _______ atm

PCl3: ______ atm

Answer 1

Solution:

Reaction and ICE

PCl5 (g) -- > PCl3 (g) + Cl2 (g)

I           0.488               0.4900             0

C         -x                     +x                    +x

E          (0.488-x)         (0.4900+x)      x

Kp = (0.4900 +x) x / (0.488 –x)

29.21 =(0.4900 +x)*x /(0.488-x)

x = 0.472

Lets find equilibrium pressure of all the species in above equation.

Equilibrium partial pressure of Cl2 = 0.472 atm

PCl5 = 0.488 atm – 0.472 atm = 0.016 atm

PCl3 = 0.4900 + 0.472 = 0.96 atm