Chemical Kinetics Question 200
Question: Hydrolysis of DDT is a first order reaction, its half life is 10 years. Time to hydrolyse 10 g DDT to half is [BVP 2004]
Options:
A) 100 years
B) 50 years
C) 5 years
D) 10 years
Show Answer
Answer:
Correct Answer: D
Solution:
$ K=\frac{0.693}{{t_{1/2}}}=\frac{0.693}{10,years} $ If initial concentration $ a=10\ gm $ and final concentration $ x=\frac{a}{2}=5\ gm $ then, $ t=\frac{2.303}{K}\log \frac{a}{a-x} $
$ =\frac{2.303}{.693}\times 10\times \log \frac{10}{5} $
$ =\frac{2.303\times 10\times \log 2}{.693} $
$ =\frac{2.303\times 10\times 0.301}{0.693}=10\ years $ .
