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Postby RyanTran2F » Sun Mar 11, 2018 5:57 pm

Hi can someone explain how the answer key got the answer in Part A? I did not quite understand the explanation provided. The question asks, "In the reaction of HBr with the reactive intermediate CH3CH=CHCH2+, at low temperatures the predominant species is CH3CHBrCH=CH2, but at high temperatures, the predominant species is CH3CH=CHCH2Br. Which product is formed by the pathway with the larger activation energy?" Thanks :)
Last edited by RyanTran2F on Tue Mar 13, 2018 5:18 pm, edited 1 time in total.

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Re: 15.79

Postby Sungyoon_Baek_1A » Mon Mar 12, 2018 1:27 pm

At high temperatures, the predominant product is CH3CHCHCH2Br. A higher temperature means that there is more energy to overcome a higher activation energy. The high temperatures and there for greater energy allow the reaction to produce CH3CHCHCH2Br. For the product CH3CHBrCHCH2, we do not need a high temperature (we do not need the greater energy to overcome a high activation energy), so we know that it has a lower activation than the pathway to form CH3CHCHCH2Br.

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Re: 15.79

Postby Chem_Mod » Mon Mar 12, 2018 1:50 pm

Please state what the question is so we can better respond to your post.

Rakhi Ratanjee 1D
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Re: 15.79

Postby Rakhi Ratanjee 1D » Tue Mar 13, 2018 12:11 am

For 15.79 part A, the answer states that CH3CH=CHCH2Br is the product because "the positive charge on the reactive intermediate is on a primary carbon atom". How can you determine that it is a product of higher temperature from this information?

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