J.R. S. answered 03/09/21
Ph.D. University Professor with 10+ years Tutoring Experience
A (g) → 3 B (g)
Kp = 0.783 = (B)3 / (A) = (0.250)3 / (5.70)
Kp = 0.00274
∆G = -RT ln K
∆G = -(0.008314kJ/Kmol)(298K) ln 0.00274
∆G =-(0.008314)(298)(-5.899)
∆G = 14.6 kJ/mol