A reaction which follows first-order kinetics has a rate constant k of 0.0942 sec-1. Given a starting concentration of 0.700 M, what is the molarity of the remaining reactant after 20.0 sec
[A] = [A0]*e^(-k*t)
[A] = 0.7*e^(-0.0942*20)
I'll leave you to do the number crunching (you can just enter the right-hand side into the calculator on the home page here).
