A sealed 1.0-L flask, initially containing 0.20 M COCl2, 0.20 M Cl2, and 0.20 M

ID: 1070134 • Letter: A

Question

A sealed 1.0-L flask, initially containing 0.20 M COCl2, 0.20 M Cl2, and 0.20 M CO, is heated to 700 K

and allowed to come to equilibrium.

COCl2(g) Cl2(g) + CO(g) Kc = 0.12 at 700 K

a. What are the molar concentrations of COCl2, Cl2, and CO once the reaction has reached equilibrium

at 700 K?

COCl2:_______________________________

Cl2:_______________________________

CO:_______________________________

b. 0.10 mol COCl2 is added to the equilibrium mixture. What are the molar concentrations of COCl2,

Cl2, and CO once equilibrium is re-established?

COCl2:_______________________________

Cl2:_______________________________

CO:_______________________________

COCl2(g) Cl2(g) + CO(g)

I 0.2 0.2 0.2

C -x +x +x

E 0.2-x 0.2+x 0.2+x

Kc = [Cl2][CO]/[COCl2]

0.12 = (0.2+x)(0.2+x)/(0.2-x)

0.12*(0.2-x) = (0.2+x)(0.2+x)

x = -0.033

[COCl2] = 0.2-(-0.033) = 0.233M

[CO] = 0.2+x = 0.2-0.033 = 0.167M

[Cl2] = 0.2+x = 0.2-0.033 = 0.167M

COCl2(g) Cl2(g) + CO(g)

I 0.1 0 0

C -x +x +x

E 0.1-x +x +x

Kc = [CO][Cl2]/[COCl2]

0.12 = x*x/0.1-x

x2 = 0.12*(0.1-x)

x = 0.065

[COCl2] = 0.1-x = 0.1-0.065 = 0.035M

[CO] = x = 0.065M

[Cl2] = x = 0.065M

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