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admin
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 Posted: Sat Jul 14, 2007 10:38 pm Post subject: |
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| Protonation is adding a proton (H+) and of course "mono" means one. Thus monoprotonation means to add one proton. |
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admin
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| Posted: Mon Jul 16, 2007 6:58 pm Post subject: |
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Answer choice D is the shorthand way that we usually draw the molecule. However, it does not really make sense. The reason is that the molecule contains an acid (-COOH) and it contains a base (-NH2). Thus the acid gives up the proton and becomes a carboxylate anion (-COO - ) and the base accepts the proton becoming -NH3+. This is called an amphoteric molecule and answer choice B is also consistent with what the molecule would look like at its isoelectric point. These are all concepts commonly tested on the MCAT.
The other way that you can look at this problem is by answering the following question: you have one proton available and it can go to one of 2 locations. Which of the following is the stronger base: -NH2 or -COO-. Recall that -COO- is resonance stabilized and that -COOH is an acid. So the answer is -NH2. |
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admin
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| Posted: Thu Jul 30, 2009 8:11 am Post subject: |
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boshenliu34457
Joined: 20 Jul 2011
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| Posted: Thu Jul 28, 2011 10:27 pm Post subject: |
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| Shouldn't the answer be C? can you please explain why C is wrong? |
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