first i wanted to say you look preety LOL
1) Determine the rate constant for the reaction:
k = (ln 2) / t_1/2 <--- I'll leave you to figure out how that came to be. Hint: use the integrate form of the first-order rate law
k = (ln 2) / 23.6 min
k = 0.02937 min^-1 <--- keep a few extra digits
1) use the integrated form of the first-order rate law:
ln A = -kt + ln A_o
ln A = - (0.02937 min^-1) (120 min) + ln 2.50
ln A = -3.5244 + 0.91629
ln A = -2.60811
A = 0.07367 M <--- round off more as you see fit
Here's another way:
120 min / 23.6 min = 5.106383 half-lives
(0.5)^5.106383 = 0.02902856 <--- the decimal amount remaining after 5.106383 half-lives
0.02902856 x 2.50 M = the answer
