Chemistry

Chemistry

Problem

The pKapK_a values of two phenolic acids at 298 K298\,\text{K} are given below. • Phenol: pKa=10.00pK_a = 10.00 • pp-Nitrophenol: pKa=7.15pK_a = 7.15 For any acid, the standard free energy of deprotonation is related to its pKapK_a by ΔG∘=2.303 R T pKa,\Delta G^\circ = 2.303\, R\, T\, pK_a, where R=8.314 J⋅mol−1⋅K−1R = 8.314\,\text{J}\cdot\text{mol}^{-1}\cdot\text{K}^{-1} and T=298 KT = 298\,\text{K}. a. Part 1: (a) Calculate ΔG∘\Delta G^\circ (in kJ⋅mol−1\text{kJ}\cdot\text{mol}^{-1}) for the deprotonation of phenol. b. Part 2: (b) Calculate ΔG∘\Delta G^\circ (in kJ⋅mol−1\text{kJ}\cdot\text{mol}^{-1}) for the deprotonation of pp-nitrophenol. c. Part 3: (c) Determine ΔΔG∘\Delta\Delta G^\circ, the difference in standard free energy of deprotonation between the two acids, and state which conjugate base is thermodynamically more stable.

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