Question

Reaction $⟹A+B\to$ product. Calculate its half life period.

$\begin{array}{ccc}\left[A_0\right]& \left[B_0\right]& Rate\left[R_0\right]\\ Mollitr{e}^{-1}& mollitr{e}^{-1}& mollitr{e}^{-1}se{c}^{-1}\\ 0.1& 0.2& 0.05\\ 0.2& 0.2& 0.10\\ 0.1& 0.1& 0.05\end{array}$

• A. $1.386se{c}^{-1}$
• B. $13.86se{c}^{-1}$
• C. $26.72se{c}^{-1}$
• D. $2.672se{c}^{-1}$

Answer 1

The correct option is A $1.386se{c}^{-1}$

When the concentration of A is doubled and the concentration of B is kept constant, the rate of the reaction is doubled. Hence, the reaction is first order in A.
The rate law expression is $r=k\left[A\right].$
Substitute values in the above expression.
$0.05=k\times 0.1$
$k=0.5$
Half life period $t_{1/2}=\frac{0.693}{k}=\frac{0.639}{0.5}=1.386se{c}^{-1}.$