Experiment: To determine the percentage of ethanoic acid in vinegar.

Vinegar is a solution of ethanoic acid dissolved in water. The purpose of this titration is to find the percentage of this acid in the vinegar.


  • Add 50 ml of vinegar to a volumetric flask using a 25 ml pipette twice.
  • Make up the solution to the 250 ml mark with deionised water. This is the solution which will be used for the titration.
  • Note: diluting the solution in this manner is necessary for two reasons (i) you will use less reagents this way and (ii) if an error is made measuring a dilute solution it will not have great implications for the final answer.
  • Add 20 ml of 0.1 M sodium hydroxide solution to the conical flask using a pipette.
  • Add two or three drops of phenolphthalein indicator, just enough to impart a pink tinge to the sodium hydroxide solution.
  • Put the dilute vinegar solution in the burette.Titrate in the usual manner.
  • The end-point is reached when the pink colour changes to colourless.
  • Record the volume of acid used from the burette.Repeat the titration several times until two titration values agree to within 0.2 ml of each other.

Equation for titration


  • Volume of acid used = 13 ml
  • Factor for the acid = 1
  • Molarity of the acid = ?
  • Volume of base used = 20 ml
  • Factor for the base = 1
  • Molarity = 0.1 M