In a first-order reaction A B, if k is rate constant and initial concentration of the reactant A is 0.5 M, then the half-life is
- 2k
- 2k 0.5
- 2k
- 0.6930.5k
Answer
(3) 2k
Solution
For a first order reaction, k = 1t [A]0[A]
At t = t1/2, [A] = [A]02
⇒ t1/2 = 2k = 0.693k
∴ The half-life is independent of the initial concentration (0.5 M is not needed).
Answer: (3)