Question

Suppose our unknown acid was acetic acid, CH3COOH (Ka = 1.8 x 10-5) and that your initial aqueous solution contained 0.100 mol of acetic acid in total volume of 100 mL.

To this acetic acid solution you begin adding a 1.0 mol/L NaOH solution. Let's see what happens after adding different amounts of NaOH.

Suppose you have added a total of 20.0 mL of NaOH solution since the beginning of the titration. How many mol of acetate ions (CH3COO–) are present in the reaction mixture at this point?