In a zero order reaction, it takes 342 seconds for 75% of a hypothetical reactant to decompose. Determine the half-life t_{1/2} in units of seconds. Do not enter units with your numerical answer. Numeric 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