Question

A necessary step in the manufacture of sulfuric acid is the formation of sulfur trioxide, SO₃, from sulfur dioxide, SO₂, and oxygen, O₂, shown here. At high temperatures, the rate of formation of SO₃ is higher, but the equilibrium amount (concentration or partial pressure) of SO₃ is lower than it would be at lower temperatures.

2SO₂(g) + O₂(g)2SO₃(g)

(a) Does the equilibrium constant for the reaction increase, decrease, or remain about the same as the temperature increases?
(b) Is the reaction endothermic or exothermic?

1) decreases, exothermic
2) decreases, endothermic
3) increases, exothermic
4) Oincreases, endothermic
5) about the same, endothermic
6) about the same, exothermic

Answer 1

The equilibrium constant for the reaction decreases as the temperature increases, due to the exothermic nature of the reaction, where heat is released and the equilibrium shifts towards the reactants at higher temperatures. Therefore, the correct answer is (1) decreases, exothermic. option (A)

Step-by-step explanation:

The formation of sulfur trioxide (SO₃) from sulfur dioxide (SO₂) and oxygen (O₂) is a key part of the industrial process to manufacture sulfuric acid. This reaction can be represented by the following equation:

2SO₂(g) + O₂(g) → 2SO₃(g)

(a) As the temperature increases, the equilibrium constant for this reaction decreases. This is because the equilibrium shifts to favor the reactants at higher temperatures in this exothermic reaction. According to Le Chatelier's principle, an increase in temperature causes a shift in equilibrium away from the heat-producing direction.

(b) This reaction is exothermic, as indicated by the negative enthalpy change (ΔH° = -197.8 kJ). An exothermic reaction releases heat to the surroundings, and hence, the amount of products at equilibrium is lower at higher temperatures.In conclusion, considering the given information, the correct option would be (1) decreases, exothermic.