Division 4 Procedure

Fill the flask of the apparatus with about 1,5 litres of freshly boiled distilled water. Add a few pieces of pumice stone. Weigh accurately, to within 0,01 g, a quantity of product corresponding to $\frac{600}{R}g$ , where R represents the NTSS (natural total soluble solids) content. After dilution as necessary, pour into the inner tube of the apparatus. Add about 100 mg of reagent 2.3. Connect the flask to the condenser. Distil 150 ml in about 30 minutes, collecting the distillate in a 200 ml conical flask, with the tip of the condenser immersed in a small quantity of freshly boiled distilled water. Stop the procedure. Pour a few drops of phenolphthalein (2.2) into the flask and titrate the acidity using the N/50 sodium hydroxide solution (2.1) until the indicator turns a persistent pink colour. Since N/50 sodium hydroxide solution is unstable, check the titre before use with an N/10 solution of hydrochloric acid (2.4). Titration may also be made by using a pH meter.