Chemical Kinetics Question 45
Question: The reaction, $ X\to $ product follows first order kinetics. In 40 minutes the concentration of X changes from 0.1 M to 0.025 M Then the rate of reaction when concentration of X is 0.01 M
Options:
A) $ 1.73\times {10^{-4}}M\ {{\min }^{-1}} $
B) $ 3.47\times {10^{-5}}M\ {{\min }^{-1}} $
C) $ 3.47\times {10^{-4}}M\ {{\min }^{-1}} $
D) $ 1.73\times {10^{-5}}M\ {{\min }^{-1}} $
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Answer:
Correct Answer: C
Solution:
Concentration will fall from 0.1 M concentration to 0.025 M concentration within 2 half lives.
$ 2\times {T_{1/2}}=40 $ min
$ \therefore \ \ {T_{1/2}}=20 $ min Rate of reaction = K . c $ =\frac{0.693}{{T_{1/2}}}.c $
$ =\frac{0.693}{20}\times {10^{-2}}M/\min $
$ =3.47\times {10^{-4}}M/{{\min }^{-1}} $ .
