Question

The temperature coefficient of a reaction is:
(A)- Ratio of rate constants at two temperature differing by $1{}^\circ C$
(B)- Ratio of rate constants at temperatures $35{}^\circ C$and$25{}^\circ C$.
(C)- Ratio of rate constants at $30{}^\circ C$and$25{}^\circ C$
(D)- Specific reaction rate at $25{}^\circ C$

Answer 1

Hint: To answer this question we should know the definition of temperature coefficient. The temperature coefficient of a chemical reaction is the ratio of the specific reaction rates at two temperatures differing by$10{}^\circ C$.

Complete answer:
Let’s find out why some options are incorrect.
-In option (A) the difference between the temperatures is given$1{}^\circ C$. But for temperature coefficient the difference should be$10{}^\circ C$. So, this option (A) is incorrect.
-In option (B) the rates are given at temperatures $35{}^\circ C$and$25{}^\circ C$ their difference is also$10{}^\circ C$. So, option (B) is the correct answer.
Let’s see why the remaining options are incorrect.
-In option (C) the difference between the temperatures of the two rates is less than$10{}^\circ C$. So, it is incorrect.
-The specific reaction rate is the rate of reaction of the products when concentration of the reactants is unity under specific conditions. It is different from the temperature coefficient. So, option (D) is also incorrect.
Hence, the answer for the given question is option (B).

Note: The formula for calculating temperature coefficient of a reaction is given by the following relation,$\mu =\dfrac{{{k}_{t+10}}}{{{k}_{t}}}$
Where, $\mu$is the temperature coefficient, ${{k}_{t+10}}$is rate of reaction at a temperature $10{}^\circ C$greater than ‘t’, ${{k}_{t}}$ is rate of reaction at a temperature ‘t’.
For every $10{}^\circ C$rise in temperature the rate gets doubled.