Q. A first order reaction is 20% complete in 10 min. What is the rate constant of the reaction?
A) 0.223
B) 0.0223
C) 0.322
D) 0.0322
Explanation
(b)
$k = \frac{2.303}{t}\log_{10}\frac{a}{a - x}$
$= \frac{2.303}{10}\log_{10}\frac{100}{80}$
$= \frac{2.303}{10}\ \left\lbrack \log{10 - 3}\log 2 \right\rbrack$
$\ = \frac{2.303}{10}\ \lbrack 1 - 3 \times 0.3010\rbrack$
$k = 0.0223$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.