HORROCK’S HORROCK’S APPARATUSAPPARATUS

T.SHASHISREET.SHASHISREE

Horrock’s ApparatusHorrock’s Apparatus

Horrock’s water testing apparatus is Horrock’s water testing apparatus is designed to find out the dose of designed to find out the dose of bleaching powder required for bleaching powder required for disinfection of water.disinfection of water.

CONTENTSCONTENTS1.6 white cups (200ml capacity each)1.6 white cups (200ml capacity each)2.One black cup with a circular mark on 2.One black cup with a circular mark on

the inside.the inside.3.2 metal spoons (each holds 2g of 3.2 metal spoons (each holds 2g of

bleaching powder when filled level bleaching powder when filled level with the brim)with the brim)

4.7 glass stirring rods 4.7 glass stirring rods 5.One special pipette5.One special pipette6.Two droppers6.Two droppers7.Starch-iodide indicator solution7.Starch-iodide indicator solution8.Instruction folder.8.Instruction folder.

PROCEDURE :PROCEDURE :

1.1. Take 1 level spoonful of (2g) Take 1 level spoonful of (2g) bleaching powder in the black cup bleaching powder in the black cup and make it into a thin paste. add and make it into a thin paste. add more water to the paste and make more water to the paste and make up the volume up to the circular up the volume up to the circular mark with vigorous stirring. allow to mark with vigorous stirring. allow to settle. this is the stock solutionsettle. this is the stock solution

2.Fill the 6 white cups with water to be 2.Fill the 6 white cups with water to be tested, up to about a cm bellow the tested, up to about a cm bellow the brim.brim.

3.With the pipette add 1 drop of the 3.With the pipette add 1 drop of the stock solution to the 1stock solution to the 1stst cup,2 drops cup,2 drops to the 2to the 2ndnd cup and so on. cup and so on.

4.stir the water in each cup using a 4.stir the water in each cup using a separate rod.separate rod.

5. Wait for the half an hour for the 5. Wait for the half an hour for the action of chlorine.action of chlorine.

6.Add 3 drops of starch-iodide indicator 6.Add 3 drops of starch-iodide indicator to each of the white cups and stir to each of the white cups and stir again. Development of blue color again. Development of blue color indicates the presence of free residual indicates the presence of free residual chlorine.chlorine.

7. Note the first cup which shows 7. Note the first cup which shows distinct blue color. supposing the 3rd distinct blue color. supposing the 3rd cup shows blue color, then 3 level cup shows blue color, then 3 level spoonfuls or 6g of bleaching powder spoonfuls or 6g of bleaching powder would be required to disinfect 455 would be required to disinfect 455 liters of water.liters of water.

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