Question

Checking the bacterial contamination in drinking water by testing sulphide ion wiki

Answer 1

Presence of pathogenic bacteria in water can be detected by testing the sulfide content of water.

The presence of sulfide ions in water is an indicator of: 

i) High pH above 10.
ii) Sulfide producing bacteria 
iii) Diminished oxygen concentrations

Conducting the sulfide ion test:

- The sulfide ion test is conducted using an Hydrogen sulfide strip (H₂S). 

- The H₂S strip is dipped into the water to be tested for 14 to 16 hours. 

- The H₂S strip turns black if sulfide ions are present in the water. The black color is due to the ionization of the H₂S. 

---> Water that is positive for this test, contains sulfide ions and is unfit for human consumption. Sulfide ions are poisonous.

Answer 2

Take some drinking water to be tested in a bottle. Insert a hydrogen sulphide (H2S) strip into the bottle such that it is immersed in the water. Leave the bottle aside for nearly 16 hours and observe the color of the test strip. If it turns black, then the water contains sulphide ions and is not safe for consumption.