Question

queston: the pH of a white vinegar solution is 2.45. this vinager is an aquous solution of acetic acid with a density of 1.09g/mL. What is the mass percentage of acetic acid in the soulution.

What exactly do i have to do? do i set up an Ice table. What do i do with the density given?

Answer 1

First you want to determine the molarity of the acetic acid in the vinegar. For simplicity, let's call acetic acid (HC2H3O2) HAc where H stands for the H and Ac stands for the C2H3O2^- ion.
HAc ==> H^+ + Ac^-
Ka = (H^+)(Ac^-)/(HAc).
You know pH; use that to calculate H^+ which will be the Ac^- also. Knowing H^+ and Ac^-, calculate (HAc). That will give you M or moles/L HAc. KNowing moles/L (the density will tell you the mass of the 1 L of solution) and the density, calculate mass percent.