JEE Main · 2020 · Shift-ImediumCEQ-012

Consider the reaction: N2O4(g) 2NO2(g), H0 = +58\ kJ For each case, the direction in which equilibrium shifts is: (a)…

Chemical Equilibrium · Class 11 · JEE Main Previous Year Question

Question

Consider the reaction: N2O4(g)2NO2(g)\mathrm{N_2O_4(g) \rightleftharpoons 2NO_2(g)}, ΔH0=+58 kJ\Delta H^0 = +58\ \mathrm{kJ}

For each case, the direction in which equilibrium shifts is: (a) Temperature is decreased. (b) Pressure is increased by adding N2\mathrm{N_2} at constant T.

Options
  1. a

    (a) towards product, (b) towards reactant

  2. b

    (a) towards reactant, (b) towards product

  3. c

    (a) towards reactant, (b) no change

  4. d

    (a) towards product, (b) no change

Correct Answerc

(a) towards reactant, (b) no change

Detailed Solution

Step 1 — Case (a): Temperature decreased Reaction is endothermic (ΔH=+58\Delta H = +58 kJ). By Le Chatelier's principle:

  • Decreasing T removes heat \rightarrow equilibrium shifts in the direction that produces heat \rightarrow backward (toward N2O4\mathrm{N_2O_4}, reactant)

Step 2 — Case (b): Pressure increased by adding N2\mathrm{N_2} at constant T

  • N2\mathrm{N_2} is an inert gas added at constant temperature
  • At constant T, adding inert gas at constant volume \rightarrow partial pressures of N2O4\mathrm{N_2O_4} and NO2\mathrm{NO_2} unchanged
  • Qp=KpQ_p = K_p \rightarrow no change in equilibrium position

Answer: Option (3) — (a) toward reactant, (b) no change

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Consider the reaction: N2O4(g) 2NO2(g), H0 = +58\ kJ For each case, the direction in which… (JEE Main 2020) | Canvas Classes