Question

For the following reaction, Kc = 255 at 1000 K. CO(g)+Cl2(g)⇌COCl2(g) A reaction mixture initially contains a CO concentration of 0.1550 M and a Cl2 concentration of 0.175 M at 1000 K. Part A What is the equilibrium concentration of CO at 1000 K? What is the equilibrium concentration of Cl2 at 1000 K? What is the equilibrium concentration of COCl2 at 1000 K?

Answer 1

Make an ICE table,

K_c = [CoCl₂] / [Co] [Cl₂] = X / (0.1550-X) (0.175-X) = 225
X = 6.103125 - 74.25X + 225 X²
225X²-75.25X+6.103125 = 0
Solve this equation for X,
X = 0.19617 or 0.13826
But X = 0.19617 exceeds the initial concentrations so it not possible.
Hence X = 0.13826
At equilibrium,
[CO] at 1000 K = 0.1550-X = 0.1550-0.13826 = 0.01674 M
[Cl₂] at 1000 K = 0.175-X = 0.175-0.13826 = 0.03674 M
[CoCl₂] at 1000 K = 0.13826 M