Page 1 of 1

### 7.11

Posted: Sun Mar 08, 2020 6:22 pm
The rate law of the reaction 2NO(g) + 2H2(g) --> N2(g) + 2H2O(g) is rate = k[NO]^2[H2], and the mechanism that has been proposed is
Step 1: NO + NO --> N2O2
Step 2: N2O2 + H2 --> N2O + H2O
Step 3: N2O + H2 --> N2 + H2O
(a) Which step in the mechanism is likely to be rate determining? Explain your answer. (b)Sketch a reaction profile for the overall reaction, which is known to be exothermic. Label the activation energies of each step and the overall reaction enthalpy.

I solved part a to get that step 2 is rate determining. So, how would you use this information to draw the reaction profile? The solutions manual shows the peaks of each elementary step reaction at different heights, but how would you know how high to draw the peaks when you don't know the activation energies of the elementary step reactions?

### Re: 7.11

Posted: Sun Mar 08, 2020 8:07 pm
The rate-determining step would have the highest activation energy, so that would have the largest hump. I am not too sure how to differentiate between the other two steps.