Question

Consider the reaction, $2A+B\to$ Products, When concentration of B alone was doubled, the rate did not change. When the concentration of A alone was doubled, the rate increased by two times. The unit of rate constant for this reaction is:

• A. $s^{-1}$
• B. $Lmo{l}^{-1}{s}^{-1}$
• C. Unitless
• D. $mol{L}^{-1}{s}^{-1}$

Answer 1

The correct option is A $s^{-1}$

When the concentration of B alone was doubled, the rate did not change. Hence the reaction is zero order in B.

When the concentration of A alone was doubled, the rate increased by two times. Hence, the reaction is of first-order in A.

$r=k{\left[A\right]}^1{\left[B\right]}^0$

The overall order of the reaction is 1.

For the first-order reaction, the unit of k is $se{c}^{-1}$.

Hence, the correct option is $\text{A}$