Vitamin C, which is ascorbic acid, is a diprotic acid with $\mathrm { p } K _ { \mathrm { a }_{1} }$ = 5.00 and $\mathrm { p } K _ { \mathrm { s }_{2} }$
= 11.3. What is
The pH of a 0.125 M solution of ascorbic acid?

Question

Quizplus · Accepted Answer

For a diprotic acid, the first dissociation is the most significant in determining pH. Using the formula for weak acid dissociation, $\mathrm{pH} = \frac{1}{2}(\mathrm{pK_a} - \log C)$, where C is the concentration, we find $\mathrm{pH} \approx 2.95$.

Vitamin C, Which Is Ascorbic Acid, Is a Diprotic Acid pKa1\mathrm { p } K _ { \mathrm { a }_{1} }pKa1​​

Vitamin C, Which Is Ascorbic Acid, Is a Diprotic Acid $\mathrm { p } K _ { \mathrm { a }_{1} }$