equilibrium

Question

6) Calcium Oxide is used to remove pollutant SO2 from smokestack gases. The ΔG° of the overall reaction

CaO (s) + SO2 (g) + ½ O2 (g) ⇔ CaSO4 (s)

is -418.6 kJ. What is PSO2 in equilibrium with air (PO2 = 0.21 atm) and solid CaO?

Answer 1

First, determine a value for K.

∆Gº = -RT ln K

ln K = -∆Gº/RT = - (-418.6)(0.0821)(K)

You don't supply the temperature, so this equation cannot be solved.  Once you plug in temperature (in ºK) and solve for K, recalling that solids have an activity of 1.  So, K = 1/PSO2 x PO2^1/2 and solve for PSO2.