Find the pH of a solution that is 0.30 M benzoic acid (HBz) and 0.25 M sodium
benzoate(NaBz). Ka for benzoic acid = 6.5 x 10-5
Use the Henderson-Hasselbalch equation.
Calculate the pH of 500 mL of 0.200 M acetic acid, CH3COOH, to which 0.0750 mol of sodium acetate,NaCH3COO, has been added.
Campion high school
To find the pH of the solution, we need to determine the concentration of hydronium ions (H3O+) in the solution. We can calculate this by considering the dissociation of benzoic acid (HBz) into hydronium ions (H3O+) and benzoate ions (Bz-).
The dissociation of benzoic acid is represented by the following equation:
HBz ⇌ H3O+ + Bz-
The concentration of H3O+ ions can be represented by [H3O+], and we will assume that the concentration of Bz- ions is the same as the concentration of NaBz, which is 0.25 M.
To solve this problem, we will use the equilibrium expression for the dissociation of benzoic acid:
Ka = [H3O+][Bz-] / [HBz]
Given Ka = 6.5 x 10^-5, [Bz-] = 0.25 M, and [HBz] = 0.30 M, we can rearrange the equation to solve for [H3O+].
6.5 x 10^-5 = [H3O+](0.25) / (0.30)
Now, we can calculate [H3O+].