Four aqueous reactions are carried out at 298 K. The measured equilibrium constants are listed in Table 2.
Table 2 – Equilibrium constants at 298 K
Reaction A K = 4.5 × 10³
Reaction B K = 1.2 × 10⁻²
Reaction C K = 0.98
Reaction D K = 7.0 × 10⁻¹
(a) Rank the standard free-energy changes (ΔG°) for the four reactions from the most negative value to the most positive value. Clearly indicate any pairs that are expected to be nearly equal.
(b) Calculate the numerical value of ΔG°, in kilojoules per mole, for Reaction A and for Reaction B. Show all work and report each answer to three significant figures.
(c) For each of the two reactions calculated in part (b), interpret the sign and magnitude of ΔG° in terms of the relative concentrations of products and reactants present at equilibrium.