Question

For a first order reaction $A \rightarrow$ Products, initial concentration of $A$ is $0.1 \,M$, which becomes $0.001 \,M$ after $5$ minutes. Rate constant for the reaction in $\min ^{-1}$ is

• A. $0.2303$
• B. $1.3818$
• C. $0.9212$
• D. $0.4606$

Answer 1

Answer: (C)

A $\rightarrow$ Products
Initial conc. $A _{ o }=0.1 \,M$
Conc. After $5 \min A_{t}=0.001\, M$
$t =5 \min$.
For first order reaction
$K =\frac{2.303}{ t } \log \left(\frac{ A _{ o }}{ A _{ t }}\right)$
$=\frac{2.303}{5} \log \left(\frac{0.1}{0.001}\right)$
$K =0.9212 \min ^{-1}$