Question
Question: In a first order reaction, the concentration of the reactant decreases from 0.8 M to 0.4 M in 15 min...
In a first order reaction, the concentration of the reactant decreases from 0.8 M to 0.4 M in 15 minutes. The time taken for the concentration to change from 0.1 M to 0.025 M is :
A
30 minutes
B
15 minutes
C
7.5 minutes
D
60 minutes
Answer
30 minutes
Explanation
Solution
The concentration fo the reactant decreases from 0.8 M to 0.4 M in 15 minutes, i.e., t1/2 = 15 minute. Therefore, the concentration of reactant will fall from 0.1 M to 0.025 in two half live. i.e., 2t1/2 = 2 × 15 = 30 minutes.