Question

Part B

At 25 ∘C the reaction from Part A has a composition as shown in the table below.

Substance	Pressure (atm)
C2H2(g)	4.75
H2(g)	3.45
C2H6(g)	4.25×10−2

What is the free energy change, ΔG, in kilojoules for the reaction under these conditions?

Answer 1

C2H2 + 2H2 -----------------> C2H6

4.75      3.45                          4.25 x 10^-2

Qp = P_C2H6 / P_C2H2 P_H2²

      = 4.25 x 10^-2 / (4.75) (3.45)^2

       = 7.52 x 10^-4

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

T = 273 + 25 = 298 K

$\dpi{100} \Delta$G   = $\dpi{100} \Delta$ Go + RT lnQp

$\dpi{100} \Delta$G   = $\dpi{100} \Delta$ Go + 2.303 RT log Qp

        = -242.1 + 2.303 x 8.314 x 10^-3 x 298 x log (7.52 x 10^-4)

        = -259.9 kJ

$\dpi{100} \Delta$G = -259.9 kJ