For the combustion of gaseous sulfur dioxide to form sulfur trioxide
2 SO₂(g) + O₂(g) → 2 SO₃(g)
heats of reaction are difficult to measure directly, so a team records ΔG at four temperatures (1.00 bar constant pressure):
T (K) 275 300 325 350
ΔG (kJ mol⁻¹) –250 –240 –229 –217
Answer the following questions about the data set.
(a) Plot ΔG versus T on appropriately scaled axes. Draw the best straight line that fits the four data points.
(b) Determine the numerical values of ΔH and ΔS (with units) for the reaction by analyzing your graph. Show all work.
(c) Using your ΔH and ΔS values, calculate ΔG at 298 K and compare it with the tabulated value provided for 300 K. Comment on the consistency.
(d) The industrial contact process typically operates near 700 K. Use your linear relationship to predict ΔG at 700 K and state whether the forward reaction remains thermodynamically favorable at that temperature.