At what point does the isoelectric point or pI occur?
A) when all of the acidic protons are neutralized with base
B) at pH = 7.0
C) at the pH when all negative charges on a zwitterion counter the positive charges
D) when the molecule has a single electric charge

Question

Quizplus · Accepted Answer

The isoelectric point or pI is the pH at which a molecule has no net charge. This occurs when all of the positive charges on a zwitterion are neutralized by negative charges and when all of the negative charges are neutralized by positive charges. This means that the number of positive charges equals the number of negative charges, resulting in a net charge of zero. Therefore, choice C is the best answer.

At What Point Does the Isoelectric Point or PI Occur