Slow and Fast Step


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CNourian2H
Posts: 106
Joined: Fri Aug 30, 2019 12:16 am

Slow and Fast Step

Postby CNourian2H » Sat Mar 14, 2020 1:44 pm

just to clarify, the slow step determines the rate of the overall rxn by determining the reaction order?

Goyama_2A
Posts: 107
Joined: Sat Aug 24, 2019 12:17 am

Re: Slow and Fast Step

Postby Goyama_2A » Sat Mar 14, 2020 1:47 pm

yes, when determining the overall rate of reaction, you can use the slow step as the sole determinant of the rate by assuming that the other steps are so fast in relation to the slow step that their influence on the overall reaction rate is negligible.

Frank He 4G
Posts: 50
Joined: Tue Nov 12, 2019 12:19 am

Re: Slow and Fast Step

Postby Frank He 4G » Sat Mar 14, 2020 3:13 pm

Yes, if you know the order of the slow step, you can determine the rate and assume that the overall rate of the reaction is equal to it.

Amy Luu 2G
Posts: 105
Joined: Wed Sep 18, 2019 12:19 am

Re: Slow and Fast Step

Postby Amy Luu 2G » Sat Mar 14, 2020 6:25 pm

Does it matter if the order of the rates? For example if the first step rate is slow and the second step is fast does the slow step control the rate? What happens if the first step is fast and the second step is slow?

Nawal Dandachi 1G
Posts: 102
Joined: Sat Sep 28, 2019 12:16 am

Re: Slow and Fast Step

Postby Nawal Dandachi 1G » Sat Mar 14, 2020 6:28 pm

Yes, by knowing the order of the slow step, you can determine the rate of the overall reaction.

Eesha Sohail 1D
Posts: 100
Joined: Sat Aug 17, 2019 12:16 am

Re: Slow and Fast Step

Postby Eesha Sohail 1D » Sun Mar 15, 2020 6:39 am

Amy Luu 2G wrote:Does it matter if the order of the rates? For example if the first step rate is slow and the second step is fast does the slow step control the rate? What happens if the first step is fast and the second step is slow?


The slow step is always the one that controls the rate of the reaction. If there are fast steps before it, we can use the pre-equilibrium approach to incorporate the first step's rate into the overall expression.

Helen Struble 2F
Posts: 97
Joined: Sat Aug 24, 2019 12:17 am

Re: Slow and Fast Step

Postby Helen Struble 2F » Sun Mar 15, 2020 12:53 pm

Amy Luu 2G wrote:Does it matter if the order of the rates? For example if the first step rate is slow and the second step is fast does the slow step control the rate? What happens if the first step is fast and the second step is slow?


Slow step determines the rate whether it is preceded by or followed by other fast steps. If there is a fast step first, the products of the first step are the reactants of the slow step and are bottlenecked by its rate, so the entire rate is dependent on the slow step. If there is a fast step after a slow step, the fast step cannot proceed until reactants are formed, so the slow step still determines the rate.

Noe BM 1J
Posts: 50
Joined: Sat Sep 07, 2019 12:17 am

Re: Slow and Fast Step

Postby Noe BM 1J » Sun Mar 15, 2020 4:37 pm

Yes, since the slow step determines the rate of the overall reaction, it means that the order of the slow step is the same as the order of the reaction.


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