Overall reaction rate

$K = \frac{k_{forward}}{k_{reverse}}$

haleyf 2I
Posts: 12
Joined: Fri Sep 25, 2015 3:00 am

Overall reaction rate

Why is the overall rate of reaction equal to just the rate of the slowest step rather than the sum off the rates of each step?

Chem_Mod
Posts: 18400
Joined: Thu Aug 04, 2011 1:53 pm
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Re: Overall reaction rate

The slowest step essentially determines the rate of the entire mechanism. Just imagine if you're driving on the freeway from home, you may be smooth-sailing for some miles (ie. fast reactions) but once you reach the heavily congested 405 (ie. slow step) you essentially sit there in your car for hours on end. With that analogy in mind, how fast you reach your destination is primarily dependent on the time spent on the 405, rendering the fast several miles negligible.