PROTOCOL N° 2

DETERMINATION OF THE TOTAL ACIDITY
OF A WATER SAMPLE

REAGENTS

• Aqueous solution of sodium hydroxide, 0.02 mol/dm³ NaOH
• Solution of phenolphthalein acid-base indicator

PROCEDURE

1. Take 10 mL of the water sample and place it in an Erlenmeyer,
2. Add 2 drops of phenolphthalein solution,
3. Drop by drop, counting the number of drops, keep adding sodium hydroxide solution until pink colour is observed,
4. Record the results.

DATA TREATMENT

The total acidity of the studied water is calculated by the following equation:

Total Acidity / mg/L CaCO₃ = n x 5

where n is the number of added drops of sodium hydroxide solution.