Chemistry · The effect of temperature on the rate of reactions, Arrhenius theory, activation energy and its calculation, collision theory of bi-molecular gaseous reactions (no derivation)

A chemical reaction was carried out at and . The rate constants were found to be

A chemical reaction was carried out at \( 300 \mathrm{K} \) and \( 280 \mathrm{K} \). The rate constants were found to be \( K_{1} \) and \( K_{2} \) at \( 300 \mathrm{K} \) and \( 280 \mathrm{K} \) respectively. Then which of the following is true?

  • A. \( K_{1}=4 K_{1} \)
  • B. \( K_{2}=2 K_{1} \)
  • C. \( K_{2}=0.25 K_{1} \)
  • D. \( K_{2}=0.5 K_{1} \)

Step-by-step solution

The rate constant of a reaction typically increases with temperature. A common rule of thumb is that the rate constant doubles for every 10 K rise in temperature. Here, the temperature decreases by 20 K (from 300 K to 280 K), so the rate constant is expected to decrease by a factor of (1/2)^2 = 1/4. Thus, K2 = 0.25 K1.
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