Question

A <-> B <-> C

delta G⁰ for A<-> B= 11.4 kJ/mol^-1

delta G⁰ for B<->C= -22.8kJ/mol^-1

A. What is the dela G⁰ for the conversion of A to C?

B. Write an equation for the free energy change (delta G) of the first reaction, A to B, taking into aaccount concentraions of reactants and products.

C. At equilibrium, what are the concentration rations of [B]/[A], [C]/[B], and [C]/[A]?

Answer 1

A)

dG for A->C

dGtotal = dG1 + dG2 = 11.4-22.8 = - 11.4 kJ/mol

b)

apply:

Q = [C]/[A]

dG1 = G°1 + RT*ln(Q1)

dG1 = G°1 + RT*ln([B]/[A])

dG2 = G°2 + RT*ln(Q2)

dG2 = G°2 + RT*ln([C]/[B]

add all

dGtotal = dG1+dG2 = G°1 + RT*ln([B]/[A]) + G°2 + RT*ln([C]/[B]

dGtotal = dG1+dG2 = (G°1+G°2) + RT*(ln([B]/[A]) + ln([C]/[B])

dGtotal = dG1+dG2 = (G°1+G°2) + RT*(ln([C]/[A])

C)

at equilbirium, the concentrations of all species must be equal to 1

since this is the basis of equilibrium:

Q = 1

Q = [B]/[A] = 1

Q= [C]/[B] = 1

so

[C]/[A] = 1