Three elementary steps are proposed for a laboratory synthesis: (1) A B C (2) C D (3)…

CHEMISTRY · Single correct · A Level · Chemistry · Thermodynamics · Thermodynamics

Problem

Three elementary steps are proposed for a laboratory synthesis: (1) A + +\,B →\rightarrow C ΔG∘=+25 kJ mol−1\Delta G^\circ = +25\,\text{kJ mol}^{-1} (2) C →\rightarrow D ΔG∘=−10 kJ mol−1\Delta G^\circ = -10\,\text{kJ mol}^{-1} (3) D →\rightarrow A + +\,E ΔG∘=−20 kJ mol−1\Delta G^\circ = -20\,\text{kJ mol}^{-1} If all three steps proceed exactly as written, what is the standard free-energy change for the overall conversion of B to E? (a) +35 kJ mol−1+35\,\text{kJ mol}^{-1} (b) −5 kJ mol−1-5\,\text{kJ mol}^{-1} (c) −30 kJ mol−1-30\,\text{kJ mol}^{-1} (d) +15 kJ mol−1+15\,\text{kJ mol}^{-1}

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