Example 6

The livescribe is mislabeled as Example 5

Solution:

You are asked to predict the effect on reactant concentration when the temperature of an equilibrium system changes and to calculate the equilibrium constant for a reaction at a different temperature.

You are given the chemical equation and equilibrium constant at a given temperature for a reaction, the standard enthalpy change for the reaction, and a new temperature.

1. This is an exothermic reaction (?H° = -198 kJ/mol). Increasing the temperature of the system will cause the equilibrium to shift to the left, consuming SO₃ and forming additional SO₂ and O₂. The O₂ concentration will increase.
2. In this problem, T₁ = 1150 K, T₂ = 1260 K, and K₁ = 0.365. Substitute these values into the van't Hoff equation and calculate the equilibrium constant at the new temperature.K₂ = 0.0599

Is your answer reasonable? Notice that the equilibrium constant decreases as predicted for an exothermic reaction at a higher temperature.