Question

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

• A. Rate of formation of C is twice the rate of disappearance of A
• B. $t_{\frac{1}{2}}$ is a constant
• C. Unit of k is $s^{-1}$
• D. Value of k is independent of the initial concentration of A and B

Answer 1

The correct option is D Value of k is independent of the initial concentration of A and B

$-\frac{dA}{2dT}=\frac{dB}{dT}=\frac{dC}{dT}$ ,rate of formation of C is half the rate of disappearance of A. Hence first statement(A) is wrong.
It is a second-order reaction(as rate depends upon A and B), so its unit will be $L.mo{l}^{-1}se{c}^{-1}$ , hence second(B) statement is also wrong.
$t_{\frac{1}{2}}$ =$\frac{1}{ka}$, hence $t_{\frac{1}{2}}$ depends upon initial concentration, so it is not constant, hence third statement(C) is also wrong
The rate constant of a reaction depends on its temperature only and is not affected by concentration. Since the value of k for any order is independent of the initial concentration of the reactants.
Hence, Option (d) is correct.