1. The problem statement, all variables and given/known data Calculate the pH of a solution of L-glutamic acid in which the ionic species with a net charge of -1 is 5 times greater than that of the isoelectric structure. (Refer to pKa Table at end of problem set). 2. Relevant equations pKa for glutamic acid: -COOH = 2.19 -NH3+ = 9.67 -R group = 4.25 pI = 3.22 3. The attempt at a solution My understand of pI is that it is the pH of a particular molecule when the molecule has no net charge. However, I guess I am not understanding the question. What does "5 times greater than the isoelectric structure" mean?