Lesson 6 (quiz - part 3 slide 7)

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931287m
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Joined: Mon Mar 11, 2019 1:43 pm

Lesson 6 (quiz - part 3 slide 7)

Post by 931287m » Sat Apr 13, 2019 1:46 pm

What makes "LAH" a better reducing agent than "NaBH4"? I don't really get the explanation given. It seems like good oxidizing agents typically have lots of oxygens (like the video example KMnO4), so I went with the same reasoning with the hydrogens in NaBH4

Thank you!
931287m
Posts: 91
Joined: Mon Mar 11, 2019 1:43 pm

Re: Lesson 6 (quiz - part 3 slide 7)

Post by 931287m » Sat Apr 13, 2019 3:37 pm

Another video question from this lesson (part 4 - quiz on slide 11): why aren't they also classified as structural isomers? (see 2nd picture) They have the same molecular formula, but different connections. Does it have to do with the term, structural "positional" isomers? I've never heard of it termed this way. Same question with the first image. If they're a type of structural isomerism, I'd think they should still be classified as a type of structural isomer, along with being a functional group isomer
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NS_Tutor_Will
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Re: Lesson 6 (quiz - part 3 slide 7)

Post by NS_Tutor_Will » Sun Apr 14, 2019 4:03 pm

Thanks for the questions!

Here's what I found on positional isomers: "Positional isomers are constitutional isomers that have the same carbon skeleton and the same functional groups but differ from each other in the location of the functional groups on or in the carbon chain" (http://www.ochempal.org/index.php/alpha ... l-isomers/).

I wouldn't worry too much about these super specific breakdowns of different types of isomers. Most important are definitely the structural/constitutional isomers plus the E/Z distinction and the stereoisomers.
NS_Tutor_Will
Posts: 766
Joined: Fri May 25, 2018 9:15 am

Re: Lesson 6 (quiz - part 3 slide 7)

Post by NS_Tutor_Will » Sun Apr 14, 2019 4:05 pm

I would recommend just memorizing the relative strength of reducing agents rather than worrying to much about the chemistry that explains why they act in specific ways, since that's further than the MCAT is likely to require you to go. If you're curious to know more, there's an interesting discussion relating to the source of the hydride in the two reducing agents (it's the second response to the question): https://www.quora.com/Why-does-LiAlH4-r ... educe-them

Good luck with your prep!
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