Equilibrium Constant And Reaction Quotient
At a particular temperature, the equilibrium constant Kc for the reaction 2SO₂(g) + O₂(g) ⇌ 2SO₃(g) is 100. If 1 mol SO₂, 1 mol O₂ and 1 mol SO₃ are placed in a 1 L vessel, the reaction will:
Select the correct option:
Solution
Proceed in the forward direction
To determine the direction of the reaction, we calculate the reaction quotient Qc and compare it with Kc. Qc = [SO₃]²/([SO₂]²[O₂]) = (1)²/((1)²(1)) = 1. Since Qc (= 1) < Kc (= 100), the reaction is not at equilibrium and must shift in the forward direction to increase the product concentration and decrease reactant concentrations until Q equals K. The large difference between Q and K (1 vs 100) indicates the system is far from equilibrium and will produce significantly more SO₃ before reaching the equilibrium state. This comparison of Q versus K is a powerful and general method for predicting the direction of any reversible reaction.
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About This Question
- Subject
- chemistry
- Chapter
- equilibrium
- Topic
- equilibrium constant and reaction quotient
- Difficulty
- Hard
- Year
- 2025
Solution
Correct Answer:
Proceed in the forward direction
To determine the direction of the reaction, we calculate the reaction quotient Qc and compare it with Kc. Qc = [SO₃]²/([SO₂]²[O₂]) = (1)²/((1)²(1)) = 1. Since Qc (= 1) < Kc (= 100), the reaction is not at equilibrium and must shift in the forward direction to increase the product concentration and decrease reactant concentrations until Q equals K. The large difference between Q and K (1 vs 100) indicates the system is far from equilibrium and will produce significantly more SO₃ before reaching the equilibrium state. This comparison of Q versus K is a powerful and general method for predicting the direction of any reversible reaction.
This hard difficulty chemistry question is from the chapter equilibrium, covering the topic of equilibrium constant and reaction quotient. It appeared in the 2025 exam.
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