2A k B is a zero-order reaction, where k = 1.0 mol L-1 min-1. If the initial concentration of A is 2 M, then the time taken to complete 75\% of the reaction will be
- 2.0 min
- 1.5 min
- 0.75 min
- 1.0 min
Answer
(3) 0.75 min
Solution
For the reaction 2A k B:
Rate = - 12 d[A]dt = k - d[A]dt = 2k
Integrating for zero-order kinetics:
[A]0 - [A]t = 2kt
For 75\% completion, the amount of A reacted is:
[A]0 - [A]t = 0.75 [A]0 = 0.75 2 M = 1.5 M
1.5 = 2 1.0 t
t = 1.52.0 = 0.75 min
Answer: (3)