Question

A chemical reaction was carried out at 300 K and 280 K. The rate constants were found to be $K_1$ and $K_2$ respectively then

• A. $K_2\approx 0.5K_1$
• B. $K_2\approx 0.25K_1$
• C. $K_2\approx 2K_1$
• D. $K_2\approx 4K_1$

Answer 1

The correct option is B $K_2\approx 0.25K_1$

Let the rate constant at 300 K be $K_1$. Temperature decrease of ${10}^{\circ }C$, rate constant value becomes approximately half the original value.
Decrease in temperature = ${20}^{\circ }C$
The rate constant, $K_2$ at 280 C is $K_2=0.25K_1$
$K_2=0.25K_1$