A student measures equilibrium constants for the gas-phase reaction
A(g)⇌B(g)
at several temperatures. The results are displayed in the table below.
Temperature / K
K
310
3.44
335
2.58
360
2.06
385
1.68
Assume that the standard Gibbs free energy change is independent of temperature over this range.
(a) Describe quantitatively how the student should transform the data so that a linear graph can be plotted.
(b) Using the transformed data, determine the numerical value of ΔG∘ in kJ mol−1.
(c) Predict the equilibrium constant at 450 K based on your calculated ΔG∘.
(d) Suppose the experimental K at 450 K is later found to be 1.10. Analyze what this deviation reveals about the validity of the constant-ΔG∘ assumption and suggest a thermodynamic quantity that is temperature-dependent and could account for the discrepancy.