1. ΔG°′ = − RT ln K_eq   so 7.5 kJ/mol = − (8.315 J/mol-K) (298 K) ln K_eq
7500 J/mol = − 2477.87 J/mol ln K_eq
ln K_eq = − 3.03; K_eq = 0.048
If you have trouble with this, just use the 2^nd function key + ln on your calculator (the anti-ln).

a. 0.048; b. 0.048/1 or ∼ 5/100; c. − 7.5 kJ/mol

2. a.
b. K_eq = 846 (Remember to convert kJ to J before you start.)
c. less than 846/1.

3. ΔG°′ for the coupled reaction = 6.3 kJ/mole + (− 12.5 kJ/mole) = − 6.2 kJ/mole.

4. −43.0 kJ/mole
Think of it this way: This reaction + 30.5 kJ/mol = − 12.5 kJ/mol
                        This reaction = - 12.5 kJ/mol - 30.5 kJ/mol

5. a. Nucleoside diphosphate kinase (NDP kinase); energy cost = 1 ATP
b. cyclic nucleotide phosphodiesterase (0 energy cost) +
            adenylate kinase (1 ATP energy cost)

6. a. NADH + H⁺ + oxaloacetate → NAD⁺ + malate
            NADH + H⁺ + pyruvate → NAD⁺ + lactate
            NADH + H⁺ + acetaldehyde → NAD⁺ + ethanol
b. ΔE°′ = E°′ (reduction half-reaction) + E°′ (oxidation half-reaction)
            ΔE°′ for oxaloacetate = − 0.166 V + 0.320 V = 0.154 V
            ΔE°′ for pyruvate = − 0.185 V + 0.320 V = 0.135 V
            ΔE°′ for acetaldehyde = − 0.197 V + 0.320 V = 0.123 V
c. The most likely reaction is the one with the most negative ΔG, which is the one with
     the largest ΔE, so the reaction with oxaloacetate is most likely.

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