## Questions about K on pg 73 of CR

Armo_Derbarsegian_3K
Posts: 35
Joined: Sat Jul 09, 2016 3:00 am

### Questions about K on pg 73 of CR

On page 73 of the CR,

K was set equal to k1/k'1, why do we assume it is for the NO+NO<->N2O2 reaction? Why is K not equal to [NO2]^2/[N2O2][O2] reaction, k2/k'2? How do we determine this? Please elaborate this step.

Also--is "k=2k2*K" going to be given? It seems we just set it equal at the end to meet the observed rate but how was this determined, unless given?

Lastly, why is the rate law 1/2 d[NO2]/dt, is this the rate to form 1 NO2?

Emma_Green_2C
Posts: 21
Joined: Wed Sep 21, 2016 2:57 pm

### Re: Questions about K on pg 73 of CR

You would select the first equation because it's the fast step. A buildup of the the intermediate causes the 1st step to be in equiilbrium. You need to use this first step to solve for the intermediate which you can then plug into the rate law for the slow step. I believe the 1/2 is because the coefficient in the equation is 2 for NO2. I think that k=2k2*K would not be given, but this step is essentially gathering together all of the constants and calling them collectively "K." Hope this helps!