Chemical Kinetics Question 299
Question: A first order reaction is half-completed in 45 minutes. How long does it need for 99.9% of the reaction to be completed-
Options:
A) 20 hours
B) 10 hours
C) $ 7\frac{1}{2} $ hours
D) 5 hours
Show Answer
Answer:
Correct Answer: C
Solution:
[c] $ k=\frac{0.693}{45} $ further $ t=\frac{2.303}{0.693}\times 45\log \frac{100}{100-99.9} $
$ =\frac{2.303\times 45\times 3}{0.693}=7\frac{1}{2}hours. $
