Chemical Kinetics Question 86
Question: A reaction that is of the first order with respect to reactant A has a rate constant $ 6{{\min }^{-1}}. $ If we start with $ [A]=0.5,mol{l^{-1}} $ , when would $ [A] $ reach the value 0.05mol $ {l^{-1}} $ [KCET 2000]
Options:
A) 0.384 min
B) 0.15 min
C) 3 min
D) 3.84 min
Show Answer
Answer:
Correct Answer: A
Solution:
We know that for first order kinetics
$ k=\frac{2.303}{t}\log \frac{a}{a-x} $
$ (a-x)=0.05mol{l^{-1}} $ , $ 6=\frac{2.303}{t}\log \frac{0.5}{0.05} $ or $ t=\frac{2.303}{6}\log \frac{0.5}{0.05}=\frac{2.303}{6}=0.384,\min $
