# Question 69afb

Feb 24, 2018

b) $\text{pH} = 3$

#### Explanation:

At $\text{pH} = 3$, glutamate is in the zwitterionic form:

"HOOC"-"CH"_2-"CH"_2-"CH"-("NH"_3^(+))("COO"^(-)) #

and has no net charge, whilst at $\text{pH} = 2.19$, it has one half net positive charge, at $\text{pH} = 4.25$, it has about half net negative charge. At $\text{pH} = 7$ it has one net negative charge and at $\text{pH} = 9.25$, it has a one and half net negative charge.

The more net charges (positive or negative) on the molecule, the better will be the solvation by polar solvents like water.