t1/2=k0.693 For a second-order reaction, the half-life depends on the rate constant and the concentration of the reactant and so is expressed as The half-ife of a reaction, t1/2, is the time it takes for the reactant concentration [A] to decrease by half. For example, after one halt-life the concentration falls from the initial concentration [A]0 to [A]0/2, after a second half-life to [A]0/4, after a third half-life Part A to [A]0/8, and so on. on. t1/2=kA01 A certain first-order reaction (A products) has a rate constant of 9.30103s1 at 45C. How many minutes does it take for the concentration of the reactant, [A], to drop to 6.25% of the original concentration? Express your answer with the appropriate units. Part B A certain second-order reaction ( B products) has a rate constant of 1.05103M1s1 at 27C and an initial half-life of 228s. What is the concentration of the reactant B after one half-iffe? Express your answer with the appropriate units