Chemical Kinetics Ques 1
1. The rate constant for a first order reaction is $4.606 \times 10^{-3} s^{-1}$. The time required to reduce 2.0 $g$ of the reactant to $0.2 g$ is :
[2020]
(a) $200 s$
(b) $500 s$
(c) $1000 s$
(d) $100 s$
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Answer:
Correct Answer: 1.(b)
Solution:
(b) First order rate equation is
$k=\frac{2.303}{t} \log \frac{[A_0]}{[A]}$
$\Rightarrow 4.606 \times 10^{-3}=\frac{2.303}{t} \log \frac{2}{0.2}$
$\Rightarrow t=\frac{2.303}{4.606 \times 10^{-3}} \times \log 10=\frac{10^{3}}{2}=500 sec$
BETA
