Question

For a first-order reaction, the half-life is constant. It depends only on the rate constant k and not on the reactant concentration. It is expressed as t 1/2 = 0.693 k For a second-order reaction, the half-life depends on the rate constant and the concentration of the reactant and so is expressed as t 1/2 = 1 k[A ] 0 Part A A certain first-order reaction ( A→products ) has a rate constant of 9.90×10−3 s −1 at 45 ∘ C . 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. View Available Hint(s) nothing nothing Submit Part B A certain second-order reaction ( B→products ) has a rate constant of 1.35×10−3 M −1 ⋅ s −1 at 27 ∘ C and an initial half-life of 240 s . What is the concentration of the reactant B after one half-life? Express your answer with the appropriate units. View Available Hint(s) nothing nothing Submit Provide Feedback Next

Answer 1