The rate law for the reaction A → products is rate = 4.36 * 10-2 M-1s-1 [A]2. What is the half-life of the reaction if the initial concentration of A is 0.250 M?

The formula for the half life is simply:

t1/2 = ln 2 / k

where k is the rate constant and can be calculated from the formula:

rate = k [A]

where [A] is the initial concn = 0.25 M

k = 4.36 * 10-2 M s-1 / 0.25 M = 0.1744 s-1

t1/2 = ln 2 / 0.1744 s-1

t1/2 = 3.97 s