posted by Marcus .
In a given 1st order reaction A ---> products, the initial concentration of A is 0.40 M. What will be the concentration of A after 15 seconds if the half-life of the reaction is 3 seconds?
I found the concentration to be 1.25 x 10-2 M
But then how do I find the rate constant of the reaction for this problem?
k = 0.693/half life