Chemistry
posted by Sara on .
The halflife for the secondorder reaction of a substance A is 58.2 s when A0 = 0.63 mol L1 Calculate the time needed for the concentration of A to decrease to the following values.
(a) onethird of its original value
(b) onesixth of its original value
(c) oneseventh of its original value

What's wrong with substituting values into the second order equation and solving for time.
Could it be you don't know how to handle 1/3, 1/6, 1/7 th values?
If Ao = 0.63 then 1/3 that = ? for a; 1/6 that for b and 1/7 that for c. 
I don't understand how to figure out K.
I used the information in the problem given to solve for k, and then plug that k in to solve for t, but it's not the correct answer. 
t_{1/2} = [1/k(Ao)]

I understand, but what is K or how can I determine K?

The problem GIVES you the half life. Use that and the equation I provided above to determine k.