COMEDK · Chemistry · 19. Chemical Kinetics

Two statements, One Assertion (A) and the other Reason (R) are given. Choose the right option.
Assertion: The rate constant \((\mathrm{k})\) for a chemical reaction gets nearly doubled for a \(10^{\circ}\) rise in temperature.
Reason: The number of bimolecular collisions between reactant molecules increase with increase in temperature

A A is wrong but \(R\) is correct.
B Both \(A\) and \(R\) are correct but \(R\) is not the correct explanation of \(A\).
C Both \(A\) and \(R\) are correct and \(R\) is the correct explanation of \(A\).
D A is correct but R is wrong.

Verified Solution

Answer & Solution

Correct Answer

(B) Both \(A\) and \(R\) are correct but \(R\) is not the correct explanation of \(A\).

Step-by-step Solution

Detailed explanation

The rate constant \(k\) of a reaction is given by the Arrhenius equation \(k = A e^{-E_a / RT}\). For most reactions, a \(10^{\circ}C\) rise in temperature leads to a doubling or tripling of the rate constant. This is primarily due to the increase in the fraction of molecules…

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

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