At , the thermal energy per mole of particles is approximately . A chemist is…
CHEMISTRY · Multi-part · AP · Chemistry · Thermodynamics and Electrochemistry · Thermodynamics and Electrochemistry
Problem
At 298K, the thermal energy per mole of particles is approximately 2.5kJ.
A chemist is studying the reversible reaction
X(g)⇌Y(g)
and measures the standard free-energy change, ΔG∘, for three different modifications of the reaction conditions (such as different isotopologues or catalysts). The values obtained are listed below.
Trial 1 ΔG∘=−2.0kJ mol−1
Trial 2 ΔG∘=+0.3kJ mol−1
Trial 3 ΔG∘=+5.5kJ mol−1
Answer the following questions about the position of equilibrium for each trial. No calculator is permitted.
(1) Part 1: For each trial, state whether the equilibrium mixture will consist of (i) mostly X, (ii) roughly equal amounts of X and Y, or (iii) mostly Y. Justify each choice qualitatively.
(2) Part 2: Rank the three trials from largest to smallest equilibrium constant, K, and explain your reasoning.
(3) Part 3: For Trial 2, estimate the percent of molecules present as Y at equilibrium and explain why only an approximate value is required rather than an exact calculation.