Amino Acid Ionization---PLEASE HELP (GS-7 FL PS (Question SPOILER))

[DrMula]

Here's a screen shot of the passage/problem

http://gyazo.com/48e40a5236244d6b31ab96757f9118ee

I don't understand this at all...why is 9.6 being emphasized here? Why not the isoelectric point (pH of 6)? Why is the pka of NH3+ considered but not the pka of COOH? Can't they both donate a hydrogen? I've done a lot of reading from different sources but can't get my head around this. HELP IS MUCH APPRECIATED! THANKS!

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[DrknoSDN]

It's asking for the deprotonated pH so all possible acidic hydrogens are removed.
COOH donates it's hydrogen easily but you have to raise the pH all the way to past 9.6 for the -NH3 to start giving up it's acidic hydrogen.
At that point you will have COO- and NH2 groups and a completely deprotonated glycine.

 

[NextStepTutor_1]

Remember to distinguish when the question asks for an uncharged molecule and a completely (un)protonated molecule. In this question, if they were to ask for when the charge of the molecule is negative, then, you would consider the Isoelectric point. However, in this case, they are asking for when the molecule will be predominantly deprotonated. That can only occur past the pH of the most basic functional group, in this case the NH3.