For the reaction N2 + 3H2 ⇌ 2NH3 in a vessel, after the addition of equal number of moles of N2 and H2, equilibrium state is formed. Which of the following is correct?
Correct answer: D. [H2] < [NH3]
- A. [H2] = [N2]
- B. [H2] > [N2]
- C. [H2] < [N2]
- D. [H2] < [NH3]
Explanation
Option D is correct.Let's analyze the given chemical reaction: N2 + 3H2 ⇌ 2NH3. The equilibrium state is reached when the rate of the forward reaction (N2 + 3H2 forming 2NH3) is equal to the rate of the reverse reaction (2NH3 decomposing to N2 + 3H2). At equilibrium, the concentrations of all species involved in the reaction remain constant.When an equal number of moles of N2 and H2 are added to the vessel, it means their initial concentrations are the same.In case of Option D: [H2] < [NH3]This option compares the initial concentration of H2 with the initial concentration of NH3. Since 1 mole of N2 reacts with 3 moles of H2 to produce 2 moles of NH3, the molar ratio of H2 to NH3 is 3:2. If the initial concentration of H2 is less than that of NH3, it means there is an excess of NH3, and the reaction has not yet reached equilibrium. Therefore, option D is correct.
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About Chemical Equilibrium
Reversible reactions reach dynamic equilibrium when forward and reverse rates become equal, and Le Chatelier's principle predicts the effect of changing concentration, pressure or temperature. The chapter also covers solubility product, the common ion effect, buffer action and the conditions used in Haber's process, with equilibrium shifts distinguished from changes in the equilibrium constant.
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