Question

Consider the reaction shown below. PbCO3(s) ----> PbO(s) + CO2(g) Calculate the equilibrium pressure of CO2 in the system at the following temperatures. (a) 110°C (b) 550°C

Answer 1

110+273=383K

Equilibrium constant K = P(CO2) = equilibrium presure of CO2

ΔGo = ΔHo - TΔSo

= 88.3 x 10³ - 383 x 151.3 = 30352.1 J/mol

ΔGo = -RT ln K

30352.1 = -8.314 x 383 x ln K

K = exp(-30352.1/(8.314 x 383) = 0.0000725

Equilibrium pressure of CO2 = 0.0000725 atm

(b) T = 550^oC = 823 K

ΔGo = ΔHo - TΔSo

= 88.3 x 10³ - 823 x 151.3 = -36219.9 J/mol

ΔGo = -RT ln K

-36219.9 = -8.314 x 823 x ln K

K = exp(36219.9/(8.314 x 823) = 199.02543

Equilibrium pressure of CO2 = 199.02543 atm