The reaction SO₂(g) + 2 H₂S(g) ⇌ 3 S(s) + 2 H₂O(g) is the basis of a suggested method for removal of SO₂ from power-plant stack gases. The standard free energy of each substance is given in Appendix C. (b) In principle, is this reaction a feasible method of removing SO₂?

Verified step by step guidance

1. Identify the standard free energy of formation (\( \Delta G^\circ_f \)) for each substance involved in the reaction from Appendix C.
2. Write the balanced chemical equation: \( \text{SO}_2(g) + 2 \text{H}_2\text{S}(g) \rightleftharpoons 3 \text{S}(s) + 2 \text{H}_2\text{O}(g) \).
3. Calculate the standard free energy change (\( \Delta G^\circ \)) for the reaction using the formula: \( \Delta G^\circ = \sum \Delta G^\circ_f(\text{products}) - \sum \Delta G^\circ_f(\text{reactants}) \).
4. Determine the sign of \( \Delta G^\circ \). If \( \Delta G^\circ < 0 \), the reaction is spontaneous under standard conditions, suggesting feasibility.
5. Discuss the implications of the \( \Delta G^\circ \) value in terms of the reaction's feasibility for removing \( \text{SO}_2 \) from power-plant stack gases.

Key Concepts

Gibbs Free Energy

Gibbs Free Energy (G) is a thermodynamic potential that measures the maximum reversible work obtainable from a thermodynamic system at constant temperature and pressure. A negative change in Gibbs Free Energy (ΔG) indicates that a reaction is spontaneous and can occur without external energy input. Understanding ΔG is crucial for assessing the feasibility of chemical reactions, such as the removal of SO₂ in this context.

Equilibrium Constant

The equilibrium constant (K) quantifies the ratio of the concentrations of products to reactants at equilibrium for a reversible reaction. It provides insight into the position of equilibrium and the extent to which a reaction proceeds. For the reaction in question, analyzing K can help determine whether the formation of products (S and H₂O) is favored over the reactants (SO₂ and H₂S), indicating the feasibility of SO₂ removal.

Le Chatelier's Principle

Le Chatelier's Principle states that if a dynamic equilibrium is disturbed by changing the conditions, the system will adjust to counteract the change and restore a new equilibrium. This principle is essential for understanding how changes in concentration, pressure, or temperature can affect the reaction's direction and feasibility, particularly in the context of removing SO₂ from stack gases.