I have no idea if this is an appropriate post (and if it is whether it’s in the right area), but I was hoping to get some help with a biochemistry question! Thank you in advance for your time.
A compound is known to have a free amino group with a pKa of 8.8, and one other ionizable group with a pKa between 5 and 7. To 100 mL of a 0.2 M solution of this compound at pH 8.2 was added 40 mL of a solution of 0.2 M hydrochloric acid. The pH changed to 6.2. The pKa of the second ionizable group is…?
I know the answer involves use of the Henderson-Hasselbalch equation and probably involves calculating the change in the moles of acid and base, but the second ionizable group thing is throwing me off. I appreciate the assistance !