8.2.4 Test for Chlorine

The test for chlorine involves the use of litmus paper, which is a type of pH indicator paper. Litmus paper is typically impregnated with a mixture of dyes that change colour in the presence of acidic or basic substances.

To perform the test, a small piece of litmus paper is moistened with water to make it damp. The damp litmus paper is then exposed to chlorine gas by placing it near the source of the gas or inserting it into a container where the gas is present.

If chlorine gas is present, it will react with the damp litmus paper. Chlorine is a strong oxidising agent, and it has a bleaching effect on many substances, including dyes. As a result, the chlorine gas will bleach the colour of the litmus paper, causing it to turn white or lose its original colour.

The change in colour of the litmus paper from its original colour to white or colourless is an indication of the presence of chlorine gas.

Conclusion

The test for chlorine using litmus paper provides a simple and visual way to confirm the presence of chlorine gas. The bleaching or whitening of the litmus paper is a clear indication of the presence of chlorine. This test is commonly used in various applications, including swimming pool testing, water treatment, and chemical laboratories.