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Topic: Rate determining step to rate equation conversion  (Read 565 times)

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Offline hellwraiz

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Rate determining step to rate equation conversion
« on: December 24, 2021, 02:15:58 PM »
These are the steps for a reaction.

CH3COCH3 + H+  ::equil:: CH3C(OH)CH3                 fast
CH3C(OH)CH3 → CH3C(OH)=CH2 + H+           slow
CH3C(OH)=CH2 + I2 → CH3COCH2I + HI      fast

My question is, why is the rate equation rate = k[CH3C(OH)CH3][H+] and not rate = k[CH3C(OH)CH3][H+][CH3C(OH)=CH2]

These equations are from a past paper and they did not show me the states of the molecules

Offline sjb

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Re: Rate determining step to rate equation conversion
« Reply #1 on: December 24, 2021, 03:01:53 PM »
What are your understandings of the speeds of the reactions?

Offline Orcio_87

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Re: Rate determining step to rate equation conversion
« Reply #2 on: December 24, 2021, 03:06:05 PM »
Quote
My question is, why is the rate equation rate = k[CH3C(OH)CH3][H+] and not rate = k[CH3C(OH)CH3][H+][CH3C(OH)=CH2]
This would mean that reaction is somehow second order to acetone.

Why does reaction speed does not depend on concentration of iodine - I don't know.

Offline hellwraiz

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Re: Rate determining step to rate equation conversion
« Reply #3 on: December 24, 2021, 03:15:05 PM »
What are your understandings of the speeds of the reactions?
My understanding is that because the second reaction is slow, it is the rate determining step, so all the chemicals that are in that step are in the rate equation.

Offline sjb

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Re: Rate determining step to rate equation conversion
« Reply #4 on: December 24, 2021, 03:46:46 PM »
My understanding is that because the second reaction is slow, it is the rate determining step, so all the chemicals that are in that step are in the rate equation.
So why is the rate not just k[enol]?

Offline hellwraiz

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Re: Rate determining step to rate equation conversion
« Reply #5 on: December 24, 2021, 04:11:22 PM »
So why is the rate not just k[enol]?
That is kinda my question. In the pastpaper it is stated that the rate is k[CH3COCH3][H+] and I don't know why.

Offline sjb

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Re: Rate determining step to rate equation conversion
« Reply #6 on: December 24, 2021, 04:28:28 PM »
Are enols stable?

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