Question

For the reaction A(g) + 2B(g) ↔ 2C(g) ΔG^o = -34.6 kJ. What is the value of ΔG in kJ at 25^oC when the pressure of A is 1.3 atm, pressure of B is 1.5 atm, and the pressure of C is 2.7?

Answer 1

A + 2B -----------------> 2C

1.3   1.5                       2.7

Qp = P_C² / P_A P_B²

      = (2.7)^2 / (1.3) (1.5)^2

       = 2.49

R = 8.314 x 10^-3 kJ/ K mol

T = 273 + 25 = 298 K

G   = Go + RT lnQp

G   = Go + 2.303 RT log Qp

        = -34.6 + 2.303 x 8.314 x 10^-3 x 298 x log (2.49)

        = -32.34 kJ

G = -32.34 kJ