The Relationship of Free-Energy Change (ΔG) to the Concentrations of Reactants

Multiple Choice

The relationship of free-energy change (ΔG) to the concentrations of reactants and products is important because it predicts the direction of spontaneous chemical reactions.Consider, for example, the hydrolysis of ATP to ADP and inorganic phosphate (P_i) .The standard free-energy change (ΔG°) for this reaction is −7.3 kcal/mole.The free-energy change depends on concentrations according to the following equation:
ΔG = ΔG° + 1.42 log₁₀ ([ADP] [P_i]/[ATP])
In a resting muscle, the concentrations of ATP, ADP, and P_i are approximately 0.005 M, 0.001 M, and 0.010 M, respectively.At [P_i] = 0.010 M, what will be the ratio of [ATP] to [ADP] at equilibrium?

A) 1.38 × 10⁶
B) 1
C) 7.2 × 10⁻⁸
D) 5.14