Q20 / 155 · WBJEE 2024 · Chemistry

Which of the following statements is true about equilibrium constant and rate constant of a single step chemical reaction?

  • Correct answer
    A
    Equilibrium constant may increase or decrease but rate constant always increases with temperature
  • B
    Both equilibrium constant and rate constant increase with temperature
  • C
    Rate constant may increase or decrease but equilibrium constant always increases with temperature
  • D
    Both equilibrium constant and rate constant decrease with temperature

Solution

Hint : According to Van't Hoff equation $\log \left(\frac{k_2}{k_1}\right)=\frac{\Delta H}{2.303 R}\left[\frac{1}{T_1}-\frac{1}{T_2}\right]$ Where $\mathrm{k}_1$ and $\mathrm{k}_2$ are Equilibrium Constants at $\mathrm{T}_1$ and $\mathrm{T}_2$ temperature respectively. When $\Delta \mathrm{H}\gt0$ (Endothermic process) then Equilibrium Constant increases with increase in temperature When $\Delta \mathrm{H} \lt 0$ (Exothermic process) then Equilibrium Constant decreases with increases in temperature. According to Arrhenius equation $\log \left(\frac{k_2}{k_1}\right)=\frac{E_a}{2.303 R}\left[\frac{1}{T_1}-\frac{1}{T_2}\right]$ where $\mathrm{k}_1$ and $\mathrm{k}_2$ are Rate Constants at $\mathrm{T}_1$ and $\mathrm{T}_2$ temperature respectively. $\mathrm{E}_{\mathrm{a}}$ (Activation energy) $\gt0$ When temperature increases rate constant will increase

Hence, the correct answer is option: 'A'.

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