Question

A reaction has a standard free-energy change of –4.60 kJ/mol at 25 °C. What are the concentrations of A, B, and C at equilibrium if, at the beginning of the reaction, their concentrations are 0.30 M, 0.40 M, and 0 M, respectively?

Answer 1

The problem doesn't tell us what the reaction is; i.e., is this K for
A + B ==> C or for
C ==> A + B.
I am assuming it is for A + B ==> C
Use dG = -RT*lnK and solve for Kc.
Then
.............A + B ==> C
I..........0.30.0.40....0
C...........-x...-x.....x
E........0.3-x..0.4-x...x
Then substitute the E line into the Kc expression and solve for x, then evaluate the other terms.