Unit 5 - Finding Rate Law Q

Chandrasekhar · April 09, 2026, 10:10:54 PM

Hi Mam!

I was wondering could you explain how to substitute a intermediate to find a rate law again? Screenshot 2026-04-09 190858.png

uma · Reply #1 - Re: Unit 5 - Finding Rate Law Q

Rate determining step is slo
so rate = k[H2]^2
However I is the intermediate and rate law is always in terms of reactant of the overall reaction.
S we need to replace intermediate by the reactant from the fast equilbrium step which is I₂
rate = k[H2][I₂]

Key Concept (AP Chemistry level)
Intermediates (like
𝐼
I) must be eliminated.
Use equilibrium expression of fast step to substitute.
Final rate law must contain only reactants from overall reaction.

Unit 5 - Finding Rate Law Q

Chandrasekhar

uma