Question

A) The reaction of CH4 is carried out at a different temperature with an initial concentration of [CH4]= 9.1�10^?2M . At equilibrium, the concentration ofH2 is 2.0�10^?2M .

2CH4(g)?C2H2+3H2(g). Find the equilibrium constant at this temperature.

B) The reaction between CO and H2 is carried out at a different temperature with initial concentrations of[CO] = 0.35M and [H2]= 0.60M .
CO(g)+2H2(g)?CH3OH(g)
At equilibrium, the concentration of CH3OH is 0.12M . Find the equilibrium constant at this temperature.

Answer 1

A) equilibrium constant,

Kc = [C2H2][H2]^3/[CH4]^2

with [H2] = 2 x 10^-2 M

the change in concentration at equilibrium would be = 2 x 10^-2/3 = 0.01 M

we get,

equilibrium concentration of,

[CH4] = 9.1 x 10^-2 - 2 x 0.01 = 0.071 M

[C2H2] = 0.01 M

Thus,

Kc = (0.01) x (2 x 10^-2)^3/(0.071)^2 = 1.59 x 10^-5

B) Equilibrium concentrations of,

[CO] = 0.35 - 0.12 = 0.23 M

[H2] = 0.6 - 2 x 0.12 = 0.36 M

[CH3OH] = 0.12 M

equilibrium constant Kc = (0.12)/(0.23)(0.36)^2 = 4.02