Question

The rate equation for the reaction 2A + B $\to$ C is found to be: rate = k[A][B]. The correct statement in relation is/are:

• A. The value of k is independent of the initial concentration of A and B.
• B. $t_{1/2}$ is a constant.
• C. The rate of formation of C is twice the rate of disappearance of A.
• D. The unit of k must be $s^{-1}$.

Answer 1

The correct option is A The value of k is independent of the initial concentration of A and B.

From the rate equation rate $=k\left[A\right]\left[B\right]$, we can say that the reaction is first order in A and first order in B. Hence, the overall order of the reaction is 2.
(A) The value of k is independent of the initial concentration of A and B. Hence, the statement B is correct.
(B) The half life period is not constant. It is inversely proportional to the concentration of reactants. Hence, the statement B is incorrect.
(C) The rate of formation of C is one half the rate of disappearance of A.
$\frac{d\left[C\right]}{dt}=\frac{-d\left[A\right]}{2dt}$
Hence, the statement C is incorrect.
(D) The unit of k must be $mo{l}^{-1}{s}^{-1}$
Hence, the statement D is incorrect.