Question

The hydrogenation of ethylene occurs by the following equilibrium: C2H4 (g) + 2 H2 (g) 2 CH4 (g) Kp = 1.64 at 1000 K. A vessel is charged with a 1.00 atm sample of C2H4 (g) and a 1.00 atm sample of H2 (g). Estimate the pressure of methane gas after the system has reached equilibrium

Answer 1

Kp = 1.64

     C2H4 (g) + 2 H2 (g)======= 2 CH4 (g)

I    1atm         1atm                   0atm

E    1-P             1-P                     2P

Kp =    [(PCH4)^2]/[[P(C2H4)][P(H2)]^2]

1.64=   [(2P)^2]/[(1-P)*(1-2P)^2]

1-P=1        1-2P=1

1.64=(2P)^2

P=0.64atm

pressure of methane at equillibrium=2p=2*0.64=1.28atm