Q32 / 180 · KCET 2021 · Chemistry

For a reaction, $A+2 B \rightarrow$ Products, when concentration of $B$ alone is increased half-life remains the same. If concentration of $A$ alone is doubled, rate remains the same. The unit of rate constant for the reaction is

  • Correct answer
    A
    $\mathrm{s}^{-1}$
  • B
    $\mathrm{L} \mathrm{mol}^{-1} \mathrm{~s}^{-1}$
  • C
    $\mathrm{mol} \mathrm{L}^{-1} \mathrm{~s}^{-1}$
  • D
    $\mathrm{atm}^{-1}$

Solution

For the reaction, $A+2 B \longrightarrow \text { Products }$ Half-life $\left(t_{1 / 2}\right)$ remains same as $[B]$ increases for lst order, $t_{1 / 2} \propto \frac{l}{[B]}$ $\therefore$ w.r.t. $B$, reaction is of first order. Also, as $[A]$ is doubled, rate remains constant. $\therefore$ It is zero order w.r.t. $A$. $\therefore$ Rate law expression is $k[A]^{0}[B]^{1}$ $\therefore$ Overall order $=0+1=1$ $\therefore$ Unit of $k=\mathrm{s}^{-1}$

Hence, the correct answer is option: 'A'.

Relevant Questions