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Home Q & A Board Science-Related Homework Help Chemistry (Moderator: Laser_3)
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irina irina
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11 years ago
I can't figure this out:

Calculate the pH at which the R-group of lysine is 33.3% dissociated. The pKa for this group is 10.5.

so...

pH = pKa + log [A-]/[HA]

i plug in 10.5 for pKa, but what do I put in for [A-]/[HA] ?

Thanks!
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2 Replies
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wrote...
#1
11 years ago
It's 33% dissociated, so 33% of the protonated lysine (HA) has turned into A- and [A-] = 33, [HA] = 67.  Or a 1:2 ratio.
Answer accepted by topic starter
smluke2000smluke2000
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#2
Posts: 125
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11 years ago
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