Question

A key step in the extraction of iron from its ore is FeO(s)+CO(g)=Fe(s)+CO2(g). Kp=0.403 at 1000°C. This step occurs in the 700°C to 1200°C zone within a blast furnace. What are the equilibrium partial pressures of CO(g) and CO2(g) when 1.00 atm of CO(g) and excess FeO(s) react in a sealed container at 1000°C?

Answer 1

Kp = p_CO2/p_CO = 0.403, at 1000 C,

where p_CO2 and p_CO are the partial pressures of CO2 and CO, respectively, at equilibrium. FeO & Fe are not considered for equilibrium constant because they are pure solids.

Before reaction, the system contains 1.0 atm of CO. If we assume both CO2 and CO behave as ideal gases under the conditions in question, then after the reaction:

p_CO2 + p_CO = 1.0 atm

because each mole of CO that reacts with FeO produces one mole of CO2.

From the equilibrium constant equation we have that:

p_CO2 = 0.403 * p_CO

Plug this into the equation involving the sum of the partial pressures to eliminate p_CO2:

0.403*p_CO + p_CO = 1.0 atm

1.403*p_CO = 1.0 atm

p_CO = 0.734 atm

pCO2 = 1.0 - 0.734 atm = 0.266 atm