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ChemistryNEET 2024Law of mass action, Kc and Kp, Le Chatelier

Equilibrium

For the reaction 2A⇌B+C\mathrm{2A \rightleftharpoons B + C}, Kc=4×10−3K_c = 4 \times 10^{-3}. At a given time the composition of the reaction mixture is [A]=[B]=[C]=2×10−3[\mathrm{A}] = [\mathrm{B}] = [\mathrm{C}] = 2 \times 10^{-3} M. Then which of the following is correct?

  1. A.The reaction has a tendency to go in the forward direction.
  2. B.The reaction has a tendency to go in the backward direction.✓
  3. C.The reaction has gone to completion in the forward direction.
  4. D.The reaction is at equilibrium.

Solution

Qc=[B][C][A]2=(2×10−3)2(2×10−3)2=1Q_c = \frac{[\mathrm{B}][\mathrm{C}]}{[\mathrm{A}]^2} = \frac{(2\times10^{-3})^2}{(2\times10^{-3})^2} = 1, which is greater than Kc=4×10−3K_c = 4\times10^{-3}. The reaction proceeds backward to reduce QcQ_c.

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