Intermediates in pre equilibrium


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Armo_Derbarsegian_3K
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Intermediates in pre equilibrium

Postby Armo_Derbarsegian_3K » Fri Feb 24, 2017 12:57 am

When you replace the intermediate in the rate law when doing pre equ problems, what do you do if you end up with another intermediate in your answer?

ClO-+H2O<->HClO+OH- fast
HClO+I-<->HIO+Cl- slow
HIO+OH-<->IO-+H2O fast

so the rate would be k2[HClO][I-] but HClO is an intermediate;

K=[OH-][HClO]/[ClO-]=k1/k'1 omit H2O b/c assumed liquid?
solve for [HClO]= k1[ClO-]/k'1[OH-]
k2*k1[ClO-]/k'1[OH-])[I-]
and that is what the solution is, is it okay to have [OH-], a "secondary" intermediate, in the rate?

Chem_Mod
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Re: Intermediates in pre equilibrium

Postby Chem_Mod » Sat Feb 25, 2017 2:13 pm

Water/aqueous solution has H2O, H+, -OH. They are not intermediates as they are all the time present in water, and therefore can be present in rate laws if involved in the slow step of a reaction.

Some reactions are referred to as acid catalyzed and H+ is present in the rate law. Meaning the more acidic the solution the faster the reaction.

Please ask me about this in my additional review session this coming Friday March 3 at 4pm in CS50.

Shark
Posts: 12
Joined: Fri Jul 15, 2016 3:00 am

Re: Intermediates in pre equilibrium

Postby Shark » Sat Feb 25, 2017 4:46 pm

was this a homework problem?

lilyjustine_1G
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Joined: Fri Jun 17, 2016 11:28 am

Re: Intermediates in pre equilibrium

Postby lilyjustine_1G » Sat Feb 25, 2017 7:01 pm

Yes this sounds like problem 15.101

Suk Jin Song 3L
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Joined: Tue Nov 17, 2015 3:00 am

Re: Intermediates in pre equilibrium

Postby Suk Jin Song 3L » Sun Feb 26, 2017 6:02 pm

Ohhh, so the review session will also go over post-midterm materials? That's also good to hear. I had a few questions regarding chemical kinetics after Quiz 2.

Manvita_Mareboina_3K
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Re: Intermediates in pre equilibrium

Postby Manvita_Mareboina_3K » Fri Mar 03, 2017 10:09 am

I think the review session today is limited to the midterm and questions within that. But Do you know if there will be any review of the new organic material?

sas_budge_1l
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Joined: Wed Sep 21, 2016 2:55 pm

Re: Intermediates in pre equilibrium

Postby sas_budge_1l » Sun Mar 12, 2017 11:14 pm

If there is 2 transition states with 2 steps involved in a reaction, can there only be 1 intermediate or is it possible to have 2 intermediates?

Julie Barreto 3A
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Joined: Wed Sep 21, 2016 2:56 pm

Re: Intermediates in pre equilibrium

Postby Julie Barreto 3A » Sun Mar 19, 2017 6:27 pm

there can be 2 transition states in an electorphillic reaction

Julie Barreto 3A
Posts: 21
Joined: Wed Sep 21, 2016 2:56 pm

Re: Intermediates in pre equilibrium

Postby Julie Barreto 3A » Sun Mar 19, 2017 6:27 pm

usually there is one intermediate

Eric_pierce_3E
Posts: 13
Joined: Wed Sep 21, 2016 2:55 pm

Re: Intermediates in pre equilibrium

Postby Eric_pierce_3E » Sun Mar 19, 2017 6:30 pm

This was very helpful thank you


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