Answer:
228 s
Explanation:
In a zero order reaction, the formula for the half life is given as;
t1/2 = [A]o / 2k
To obtain the rate constant k, we have to use;
[A] = [A]o - kt
kt = [A]o - [A]
From the question;
it takes 342 seconds for 75% of a hypothetical reactant to decompose.
We have;
t = 324
[A] = 25
[A]o = 100
Upon solving for k we have;
kt = [A]o - [A]
k = ( [A]o - [A] ) / t
k = (100 - 25 ) / 342
k = 75 / 342 = 0.2193
Solving for t1/2;
t1/2 = [A]o / 2k
t1/2 = 100 / 2(0.2193)
t1/2 = 100 / 0.4386 = 228 s
