What is the equilibrium partial pressure?

Question

One reaction that occurs in producing steel from iron ore is the reduction of iron(II) oxide by carbon monoxide to give iron metal and carbon dioxide.

The equilibrium constant, Kp, for the reaction at 1000 K is 0.259. FeO(s) + CO(g) ⇌ Fe(s) + CO2(g) Kp = 0.259 at 1000 K.

What is the equilibrium partial pressure of CO at 1000 K if the initial partial pressures are PCO = 1.000 atm and PCO2 = 0.500 atm?

Answer 1

FeO(s) + CO(g) <==> Fe(s) + CO₂(g) ... balanced equation

Because Kp is < 1, the reaction will proceed from left to right

................1 atm......................0.5 atm.......Initial

................+x............................-x..............Change

................1+x..........................0.5-x.........Equilibrium

Kp = (CO₂) / (CO)

0.259 = 0.5-x / 1+x

0.259 + 0.259x = 0.5-x

1.259x = 0.241

x = 0.191 atm

P(CO)@ equilibrium = 1.00 + 0.191 = 1.19 atm

(be sure to check the math)