Chemical Kinetics Question 202
Question: In the first order reaction, the concentration of the reactant is reduced to 25% in one hour. The half life period of the reaction is [DCE 2004]
Options:
A) 2 hr
B) 4 hr
C) 1/2 hr
D) 1/4 hr
Show Answer
Answer:
Correct Answer: C
Solution:
$ K=\frac{2.303}{1\ hr}\log \frac{100}{25}=\frac{2.303}{t}\log \frac{100}{50} $
$ \therefore \ \ \log 4=\frac{1}{t}\log 2 $
$ \therefore \ \ 2\log 2=\frac{1}{t}\log 2 $ ; $ t=\frac{1}{2}hr $ .
