Question

The integrated rate law allows chemists to predict the reactant concentration after a certain amount of time, or the time it would take for a certain concentration to be reached. The integrated rate law for a first-order reaction is: [A]=[A]0e−kt[A]=[A]0e−kt Now say we are particularly interested in the time it would take for the concentration to become one-half of its initial value. Then we could substitute [A]02[A]02 for [A][A] and rearrange the equation to: t1/2=0.693k t1/2=0.693k This equation calculates the time required for the reactant concentration to drop to half its initial value. In other words, it calculates the half-life.

Half-life equation for first-order reactions: t1/2=0.693k where t1/2 is the half-life in seconds (s), and k is the rate constant in inverse seconds (s−1). Part A What is the half-life of a first-order reaction with a rate constant of 2.70×10−4  s−1? Express your answer with the appropriate units. Part B What is the rate constant of a first-order reaction that takes 535 secondsseconds for the reactant concentration to drop to half of its initial value? Express your answer with the appropriate units. Part C A certain first-order reaction has a rate constant of 2.40×10−3 s−1s−1. How long will it take for the reactant concentration to drop to 1818 of its initial value? Express your answer with the appropriate units.

Answer 1