Q4 / 120 · JEE Main 2007 · Chemistry

Consider the reaction, $2 \mathrm{A}+\mathrm{B} \rightarrow$ Products When concentration of $\mathrm{B}$ alone was doubled, the half-life did not change. When the concentration of $\mathrm{A}$ alone was doubled, the rate increased by two times. The unit of rate constant for this reaction is

  • Correct answer
    A
    $\mathrm{L} \mathrm{~mol}^{-1} \mathrm{~s}^{-1}$
  • B
    no unit
  • C
    $\mathrm{mol} \mathrm{~L}^{-1} \mathrm{~s}^{-1}$
  • D
    $\mathrm{s}^{-1}$

Solution

$2 \mathrm{A}+\mathrm{B} \rightarrow$ Product When conc. of $\mathrm{B}$ is doubled, the half life did not change, hence reaction is of first order w.r.t. $\mathrm{B}$. When concentration of $\mathrm{A}$ is doubled, reaction rate is doubled, hence reaction is of first order w.r.t. $\mathrm{A}$. Hence over all order of reaction is $1+1=2$ So, unit of rate constant $\mathrm{mol}^{-1} \mathrm{~lit~s}^{-1}$. Hence, (A) is correct.

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

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