Question

(A) follows first order reaction : $A\to$ Products; concentration of A changes from 0.1 M to 0.025 M in 40 minutes. Find the rate of reaction of A when its concentration is 0.01 M.

• A. $1.73\times {10}^{-4}Mmi{n}^{-1}$
• B. $1.73\times {10}^{-5}Mmi{n}^{-1}$
• C. $3.47\times {10}^{-4}Mmi{n}^{-1}$
• D. $3.47\times {10}^{-5}Mmi{n}^{-1}$

Answer 1

The correct option is C

$3.47\times {10}^{-4}Mmi{n}^{-1}$

Fraction remaining after 40 minutes
$=\frac{0.025}{0.1}=\frac{1}{4}=(\frac{1}{2}{)}^2;Hence,2\times t_{\frac{1}{2}}=40\Rightarrow t_{\frac{1}{2}}=20minutesRate=k[A]=\frac{0.693}{20}\times 0.01=3.47\times {10}^{-4}mol{L}^{-1}mi{n}^{-1}$