A Mixture Contains Benzoic Acid, a Monoprotic Acid (K_a =

Short Answer

A mixture contains benzoic acid, a monoprotic acid (K_a = 6.28 × 10⁻⁵, 0.250 M), and sodium benzoate (0.400 moles/liter). How many mL of a HCl(aq)solution whose pH is 0.523 should be added to 500 mL of this buffer to change its pH from what it is to pH = 4.20?Hint: Determine the pH of the original buffer, the original [base]/[acid] ratio, and then the target [base]/[acid] ratio.