Textbook 15.23 Part A

$\frac{d[R]}{dt}=-k[R]; \ln [R]=-kt + \ln [R]_{0}; t_{\frac{1}{2}}=\frac{0.693}{k}$

Shirley Wong 2E
Posts: 22
Joined: Fri Sep 25, 2015 3:00 am

Textbook 15.23 Part A

Determine the rate constant for each of the following first-order reactions, in each case expressed for the rate of loss of A: (a) A -> B, given that the concentration of A decreases to one-half its initial value in 1000. s.
In discussion, my TA used the formula 1/2[A]=[A]e^-kt. How do we know to put a 1/2 in the beginning of the formula?

Hannah Ship 2H
Posts: 15
Joined: Fri Sep 25, 2015 3:00 am

Re: Textbook 15.23 Part A

I believe you put the 1/2, because the question asks to you find 1/2 of the amount that remains.