Methodical guide on independent work of students.

Methodical guide on independent work of students.

Carrying out of an experienced (trial) chlorination

The purpose of carrying out of an experienced chlorination consists in definition of a necessary dose of chlorine at a chlorination by normal doses. The choice of a dose of chlorine is usually yielded for a chlorination by a method of three glassfuls in field conditions.

Technique of carrying out of a trial chlorination

Water	200 mls	200 mls	200 mls
Solution of Lime chloride 1 %	2 drops	4 drops	6 drops
Solution of Potassium iodide 5 %	5 mls	5 mls	5 mls
Solution of Hydrochloric acid: water ( 1: 3 )	1 ml	1 ml	1 ml
Solution of Amylum 1 %	1 ml	1 ml	1 ml
Solution of Sodium hyposulphitum 0, 01 n	drops up to a decolorization of contents in a flask ( 20 Drops = 1 ml of the Solution of Sodium hyposulphitum 0, 01 n)

In three conic flasks it is pour till 200 mls of researched water. In 1 flask to add 2 drops 1 % of a solution of Lime chloride, in 2 flask - 4 drops and in 3 flask - 6 drops. Contents of flasks to intermix by rotary movement and to leave for 15 minutes. After that in all flasks to add till 1 ml of a solution of a Hydrochloric acid in delution 1: 3 till 5 mls 5 % of a solution of Potassium iodide and till 1 ml 1 % of a solution of Amylum. Flasks aggressively to shake up. At presence of free Chlorine the water is colored in dark blue colour, the more Chlorine, the more intensively staining. In that flask, where all chlorine was spent – colouring will not take plcace. Chlorine as most active substanse displaces from Potassium iodide Iodum, and Iodum with Amylum gives a dark blue staining.

DEFINITION of residual CHLORINE

Residual chlorine determine in painted flasks. Solution of Sodium hyposulphitum pour from pipet by drops in a flask up to a decolorization of contents in a flask. At titration after each added drop (rotary movement) a flask to shake. Then translate an amount of drops of Sodium hyposulphitum, use on titration of water in each flask in milliliters (20 drops on the average contain in 1 ml). Determine residual quantity of chlorine in each flask under the formula:

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