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The Pka of a protein is 4. At a Ph of 5, how much will be dissociated?
a. 10%
b.90%
c.50%
d. 100%
e.99%
A patient takes aspirin daily. The Pka is 4. At a PH of 6, how much of it will be dissociated ?
a. 100%
b.99%
c.1%
d.50%
e.0%
b.
Both answers would be B
one way to remember
ph +pka +log B/A

+2 - 99%
+1 - 90%
pka - x
-1 - 10%
-2 - 1%
ph = pka + log B/A
as far as I know these concepts are no more tested in USMLE... Smile
acids don`t dissociate in acidic media and same for bases..that`s enough to remember i guess.
oops...didnt know they r not tested anymore...but they r asked in a different way i guess..like long questions n clinical scenarios getting down to this concept...anyways Happy studying..