The reversible decomposition is carried out in a sealed

CHEMISTRY · Multi-part · AP · Chemistry · Thermodynamics and Electrochemistry · Thermodynamics and Electrochemistry

Problem

The reversible decomposition F2(g)⇌2 F(g)\mathrm{F_2(g)} \rightleftharpoons 2\,\mathrm{F(g)} is carried out in a sealed, rigid container. The standard free-energy change is ΔG∘=+4.8 kJ mol−1\Delta G^\circ = +4.8\,\text{kJ mol}^{-1} at 400 K400\,\text{K}. Assume ΔG∘\Delta G^\circ is temperature-independent over the range considered. Throughout this problem, work without a calculator. (1) Part 1: At 400 K400\,\text{K}, estimate the equilibrium constant, K400K_{400}, to one significant figure and state whether the container will contain mostly F2\mathrm{F_2}, mostly F\mathrm{F}, or roughly equal amounts. Show your reasoning. (2) Part 2: The chemist wishes to obtain at least 75%75\% atomic fluorine (F\mathrm{F}) at equilibrium. Determine---using approximate calculations---whether raising the temperature to 800 K800\,\text{K} will meet this goal. Clearly outline every assumption made and justify each estimation step. (3) Part 3: Identify one experimental complication that could invalidate the assumptions made in part (b) and explain its potential effect on the predicted equilibrium composition.

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