Law Of Chemical Equilibrium
For the reaction N₂(g) + 3H₂(g) ⇌ 2NH₃(g), the equilibrium constant Kc at a certain temperature is 0.50. What is the value of Kc for the reaction NH₃(g) ⇌ ½N₂(g) + 3/2 H₂(g)?
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Solution
1.41
When a reaction is reversed and halved, the new equilibrium constant is related to the original by K'c = (1/Kc)^(1/2). The original reaction gives Kc = 0.50 for N₂ + 3H₂ ⇌ 2NH₃. Reversing it gives Kc' = 1/0.50 = 2.0 for 2NH₃ ⇌ N₂ + 3H₂. Halving the stoichiometry means taking the square root: K''c = √2.0 = 1.414 ≈ 1.41. This illustrates the key rule that when the stoichiometric coefficients of an equilibrium reaction are multiplied by a factor n, the equilibrium constant becomes Kc raised to the power n.
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About This Question
- Subject
- chemistry
- Chapter
- equilibrium
- Topic
- law of chemical equilibrium
- Difficulty
- Medium
- Year
- 2025
Solution
Correct Answer:
1.41
When a reaction is reversed and halved, the new equilibrium constant is related to the original by K'c = (1/Kc)^(1/2). The original reaction gives Kc = 0.50 for N₂ + 3H₂ ⇌ 2NH₃. Reversing it gives Kc' = 1/0.50 = 2.0 for 2NH₃ ⇌ N₂ + 3H₂. Halving the stoichiometry means taking the square root: K''c = √2.0 = 1.414 ≈ 1.41. This illustrates the key rule that when the stoichiometric coefficients of an equilibrium reaction are multiplied by a factor n, the equilibrium constant becomes Kc raised to the power n.
This medium difficulty chemistry question is from the chapter equilibrium, covering the topic of law of chemical equilibrium. It appeared in the 2025 exam.
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