Division 6.3 Determination

Using the 250 ml measuring cylinder (5.6), add 200 ml of freshly boiled and cooled water, previously heated to 60 ^o C. Stopper the flask, mix by swirling and place in the water bath at 60 ^o C (5.8) for 30 minutes. Shake the flask at intervals of about 10 minutes.

Filter, and cool the filtrate to about 20 ^oC. The filtrate must be clear.

Transfer 100 ml of the cooled filtrate into the conical flask (5.5), using the pipette (5.3). Add 0,5 ml of the phenolphtalein indicator solution (4.2), using the pipette (5.4). Titrate with the standard volumetric sodium hydroxide solution (4.1), until the appearance of a faint pink colour, persisting for at least 30 seconds. Determine and record the volume used to the nearest 0,01 ml.