Find the pH of the following acid

Question

The pH of a solution of 4.71 mol/L acetic acid in water is a.bc

Answer 1

Acetic acid is a weak acid so you need to use the equilibrium constant, K and the corresponding equation

K = [H+] x [A-] / [HA]

Where [H+] is the concentration of protons, [A-] is the concentration of the conjugate base, and [HA] is the concentration of acetic acid. Since acetic acid generates only one proton per molecule, [H+] = [A-] so you can rewrite this as

K = [H+]² / [HA]

You already know the concentration of HA from the problem and K can be found in your book or online as 1.7x10^-5.

Plug them in and get [H+] and then to convert from concentration of H+ to pH use

pH = -log([H+])