Posted by Carlo on .
Hi, I was wondering if you could possibly help me with this chem question.
For the relatively slow decomposition of NOCL into NO and Cl2 according to the reaction below, it is known that the reaction is second order w/ respect to NOCl and that after 23.4 minutes that 75% of NOCl is decomposed when the initial concentration of NOCl is 0.0732 M. How long (in minutes) would it take until 35.8% of the NOCl has decayed?
2 NOCl > 2 NO + Cl2
i think i have to use the integrated law but other than that how would i work this out? Thank you.
1/[A]=(kt + 1)/A null

Ap Chemistry 
DrBob222,
For a second order reaction, the equation is
(1/A)  (1/Ao) = akt
I think you have Ao, A, a, and t (23.4 min) so you can solve for k (at 75% decomposition).
Then use k in the revised equation. You will have k, A, Ao (for 35.8% decomposition) and a, and you can solve for t. Check my thinking.