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Rate Determining

Posted: Fri Mar 16, 2018 4:12 pm
by Pooja Nair 1C
How do you determine whether a step in a mechanism is slow or fast if they don't already give it to you?

Re: Rate Determining

Posted: Fri Mar 16, 2018 4:40 pm
by Karen Ung 2H
According to my TA, information on whether the steps in a mechanism are slow or fast will be given.

Re: Rate Determining

Posted: Fri Mar 16, 2018 7:47 pm
by 704887365
If they give you graphs with activation energy, the graph with the higher activation energy will be slower than the other bc it will take longer and more energy to carry out the reaction.

Re: Rate Determining

Posted: Fri Mar 16, 2018 8:56 pm
by Michael Downs 1L
If the slow step is listed first, then you don't have to worry about calculating any other steps listed below it

Re: Rate Determining

Posted: Sat Mar 17, 2018 2:07 am
by Jennifer Ho 1K
The slow step should be given, and the other steps are assumed to be fast.

Re: Rate Determining

Posted: Sat Mar 17, 2018 2:49 am
by GabrielGarciaDiscussion1i
One way to help determine is the the number of molecules needed to combine. So more often than not, a bimolecular reaction will be slower than a unimolecular. Then termolecular being slower than bimolecular. THIS IS NOT FOOL PROOF OR ANY KIND OF LAW TO USE 100% OF THE TIME, just something to consider. Also, look at the Activation energies.

Re: Rate Determining

Posted: Sat Mar 17, 2018 3:25 am
by Clarissa Molina 1D
Do you always ignore the reverse of the slow step? Why?

Re: Rate Determining

Posted: Sat Mar 17, 2018 11:31 am
by GabrielGarciaDiscussion1i
Clarissa Molina 1D wrote:Do you always ignore the reverse of the slow step? Why?


Well the idea is that when it comes to the slow step, the reaction produces products slowly in comparison to the other reactions so that the slow reaction can only proceed forward for a significant amount of time since there is not a significant enough amount of product to proceed with the reverse rxn. It reaches equilibrium so slowly that we can negate the reverse k for the slow reaction.