09-23-2011 at 01:46 PM
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#16
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appearntly the C-H question the one with the negative nitrogen inducing seperation of charge is the false one. I asked Dr. Yang after the midterm was over.
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09-23-2011 at 01:49 PM
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#17
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Mr.Spock is not dazzled.
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Quote:
Originally Posted by L'Étoile
appearntly the C-H question the one with the negative nitrogen inducing seperation of charge is the false one. I asked Dr. Yang after the midterm was over.
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But it makes sense... N induces a partial + in C, so it pulls the electron from H and its own closer, making H less stable and more attractive to an O/other half of an H bond...
This sucks because I knew C could Hbond (SPONC!), but the others looked better...
Well that is one wrong for me... and 1% of my final grade if I get scheme A...
Last edited by britb : 09-23-2011 at 01:52 PM.
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09-23-2011 at 01:52 PM
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#18
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N is never negative ..................... ............... i know tricky
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09-23-2011 at 01:57 PM
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#19
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Quote:
Originally Posted by L'Étoile
N is never negative ..................... ............... i know tricky
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:O That IS tricky, because it has higher EN than C anyway, you'd think it would be the - side of the molecule, at least when its sitting next to a carbon...
Yeah I still don't get it... did anyone see it in the text? I dont think I did... |
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09-23-2011 at 01:58 PM
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#20
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Quote:
Originally Posted by L'Étoile
appearntly the C-H question the one with the negative nitrogen inducing seperation of charge is the false one. I asked Dr. Yang after the midterm was over.
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That question was so crazy though. Mad ambiguity about the water answer (does it mean [H20] or [solute]?), and also the fact we could not have known the answer.... How do we know that that was for sure false. After all the NH2- anion can exist so why can't a deprotonated amine exist?Sure its likely to be some funky chemistry but so is the idea of C-H acting as a hydrogen bond donor (I have never heard this before today).
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09-23-2011 at 02:06 PM
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#21
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Quote:
Originally Posted by arathbon
That question was so crazy though. Mad ambiguity about the water answer (does it mean [H20] or [solute]?), and also the fact we could not have known the answer.... How do we know that that was for sure false. After all the NH2- anion can exist so why can't a deprotonated amine exist?Sure its likely to be some funky chemistry but so is the idea of C-H acting as a hydrogen bond donor (I have never heard this before today).
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From what I got, hydrogen bond donors give up H, and hydrogen bond acceptors have the lps. It was very confusing, because it pretty much the opposite of orgo (electrons are usually donated, not Hs).
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09-23-2011 at 02:15 PM
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#22
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Quote:
Originally Posted by britb
From what I got, hydrogen bond donors give up H, and hydrogen bond acceptors have the lps. It was very confusing, because it pretty much the opposite of orgo (electrons are usually donated, not Hs).
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It wasn't the donorship that got me (it follows the same terminology as Bronsted-Lowry, as oppose to Lewis), but C-H participating in hydrogen bonding. The textbook simply states that the donor group is weakly acidic and suggests O-H, N-H or sometimes S-H. It doesn't mention C-H, and I don't recall ever seeing a reference to C-H acting in such a manner before.
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09-23-2011 at 02:18 PM
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#23
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Mr.Spock is not dazzled.
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Quote:
Originally Posted by arathbon
It wasn't the donorship that got me (it follows the same terminology as Bronsted-Lowry, as oppose to Lewis), but C-H participating in hydrogen bonding. The textbook simply states that the donor group is weakly acidic and suggests O-H, N-H or sometimes S-H. It doesn't mention C-H, and I don't recall ever seeing a reference to C-H acting in such a manner before.
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Yes. Add to it this business about N never being negative...
I can't wait to see the distribution...
Last edited by britb : 09-23-2011 at 02:29 PM.
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09-23-2011 at 02:34 PM
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#24
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Quote:
Originally Posted by arathbon
That question was so crazy though. Mad ambiguity about the water answer (does it mean [H20] or [solute]?), and also the fact we could not have known the answer.... How do we know that that was for sure false. After all the NH2- anion can exist so why can't a deprotonated amine exist?Sure its likely to be some funky chemistry but so is the idea of C-H acting as a hydrogen bond donor (I have never heard this before today).
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The choice with the water concentration was worded weird. I don't know for sure if it was meant to mean solute concentration, or water concentration. But if it was just water concentration then that is just volume.... I hope it meant solute concentration. |
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09-23-2011 at 02:42 PM
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#25
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Quote:
Originally Posted by R633
The choice with the water concentration was worded weird. I don't know for sure if it was meant to mean solute concentration, or water concentration. But if it was just water concentration then that is just volume.... I hope it meant solute concentration.
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Do you mean the part with osmosis? That's the actual definition of it... though its the same as diffusion basically (solute moving from high to low is the same as water moving high to low, because if you have more solute, [H2O] will be less...)
If you mean the one with ice... well everyone hated that, lol. |
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09-23-2011 at 02:47 PM
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#26
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Quote:
Originally Posted by britb
Do you mean the part with osmosis? That's the actual definition of it... though its the same as diffusion basically (solute moving from high to low is the same as water moving high to low, because if you have more solute, [H2O] will be less...)
If you mean the one with ice... well everyone hated that, lol.
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No we mean in this case the osmosis one. It wasn't clear which concentration the question was referring to (water vs. solute). Water moves from low to high solute concentration or high to low water concentration. Some textbooks refer to it the first way (I'm pretty sure Biological Sciences does), but on checking our textbook refers to it in terms of water concentration. It's fair, but there's an ambiguity in the question that more tests your ability to remember which was this textbook referred to it than your actual understanding of osmosis.
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09-23-2011 at 02:50 PM
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#27
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About the C-H H-bond question, there was a question in the end of the chapter questions that mentions it. If you check the answers, it explains it.
arathbon
says thanks to bumbum for this post.
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09-23-2011 at 02:54 PM
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#28
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He is asian, his language will never be better than its now. "None of the rest" ... huh?
to be honest, no matter how many times we will complain about how profs write midterms in their own language, McMaster won't take action!
I had Ullal for sensory, there was a multiple choice question that I got wrong because of a missing comma! the missing comma changed the meaning that I understood!!! he meant the other meaning with the comma but since there was no comma I thought that he meant something else! its honestly crazy!
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Last edited by L'Étoile : 09-23-2011 at 03:02 PM.
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09-23-2011 at 02:55 PM
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#29
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Quote:
Originally Posted by bumbum
About the C-H H-bond question, there was a question in the end of the chapter questions that mentions it. If you check the answers, it explains it.
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That's actually pretty annoying. Looks like I actually have to do all the questions in case other random answers are hidden in there.
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Alasdair Rathbone
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09-23-2011 at 03:04 PM
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#30
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Mr.Spock is not dazzled.
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Quote:
Originally Posted by bumbum
About the C-H H-bond question, there was a question in the end of the chapter questions that mentions it. If you check the answers, it explains it.
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Wow, the one time in my entire student career that textbook questions are relevant. :| Next time, I guess. Thank you! |
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