Here we are estimated the residual chlorine in drinking water by the help of CHLOROSCOPE.
In this test, 10 ml of chlorinated sample of water is taken after the required contact period, in a glass tube. To this 0.1 ml of orthotolidine solution is added. The color formed is observed after 5 minutes. The formation of yellow color normally indicates the presence of chlorine (either combined or free) in the water. The more yellow the color, the greater, is the chlorine residual.
The normal range of residual chlorine is 0.2- 0.5 ppm in drinking water.
