CHEMISTRY INVESTIGATORY PROJECT
CHECKING THE BACTERIAL CONTAMINATION IN DRINKING WATER BY TESTING SULPHIDE ION
Submitted By:
Name: ____________
Class: XI
Roll No.: ____________
School: ____________
Session: ____________
Teacher: ____________
CERTIFICATE
This is to certify that ____________ of Class XI has successfully completed the Chemistry Investigatory Project titled “Checking the Bacterial Contamination in Drinking Water by Testing Sulphide Ion” under the guidance of the Chemistry teacher during the academic session ____________.
Teacher's Signature: ____________
Examiner's Signature: ____________
Date: ____________
ACKNOWLEDGEMENT
I express my sincere gratitude to my Chemistry teacher for providing valuable guidance and support throughout this project. I am also thankful to my school for providing laboratory facilities and resources necessary for completing this investigation successfully.
INDEX
- Introduction
- Aim
- Theory
- Materials Required
- Procedure
- Observations
- Result
- Conclusion
- Precautions
- Bibliography
INTRODUCTION
Water is one of the most essential natural resources required for life. Safe drinking water is necessary for maintaining good health. Water may become contaminated due to the presence of microorganisms such as bacteria, viruses, and fungi. Contaminated water can cause diseases like cholera, typhoid, dysentery, and gastroenteritis.
The sulphide test is a simple and economical method used to detect bacterial contamination in water. Certain bacteria present in contaminated water produce hydrogen sulphide gas by reducing sulphates. This gas reacts with chemicals present in the testing medium and causes a black coloration, indicating contamination.
AIM
To check bacterial contamination in different drinking water samples by testing for sulphide ion formation.
THEORY
The sulphide test is based on the principle that bacteria present in contaminated water can reduce sulphates and other sulphur compounds to hydrogen sulphide (H₂S).
Hydrogen sulphide reacts with metal salts present in the testing medium and forms black metal sulphides.
Reaction:
Hydrogen Sulphide + Metal Salt → Metal Sulphide (Black Precipitate)
The appearance of black colour indicates bacterial contamination in the water sample.
Greater blackening generally indicates higher contamination.
MATERIALS REQUIRED
- Water samples from different sources
- Test tubes or sterile bottles
- Sulphide test medium
- Dropper
- Labels
- Marker pen
- Distilled water (control sample)
- Gloves
PROCEDURE
-
Collect water samples from different sources such as:
- Tap water
- Hand pump water
- Well water
- Pond water
- Packaged drinking water
-
Label all containers properly.
-
Add equal amounts of sulphide test medium to each sample.
-
Keep the samples undisturbed at room temperature for 24–48 hours.
-
Observe the colour changes carefully.
-
Record the intensity of black coloration in each sample.
-
Compare the results with the control sample containing distilled water.
OBSERVATION TABLE
| Sample No. | Source of Water | Observation | Contamination Level |
|---|---|---|---|
| 1 | Distilled Water | No colour change | Nil |
| 2 | Packaged Water | Very slight colour change | Low |
| 3 | Tap Water | Light black colour | Moderate |
| 4 | Hand Pump Water | Dark black colour | High |
| 5 | Pond Water | Intense black colour | Very High |
RESULT
The sulphide ion test indicated varying levels of bacterial contamination in different water samples.
Pond water and hand pump water showed significant black coloration, indicating a high level of bacterial contamination.
Packaged drinking water showed the least contamination and was comparatively safer for drinking.
CONCLUSION
The experiment demonstrates that drinking water obtained from different sources contains varying amounts of bacterial contamination.
The sulphide ion test is an effective and simple method for detecting bacterial contamination in water. Water from natural and untreated sources generally contains more bacteria than purified or packaged drinking water.
Regular testing and proper purification of drinking water are essential to ensure public health and safety.
PRECAUTIONS
- Use clean and sterile containers for collecting water samples.
- Avoid touching the inside of test tubes and bottles.
- Label all samples carefully.
- Maintain identical conditions for all samples.
- Record observations accurately.
- Wear gloves while handling samples.
- Dispose of test materials safely after the experiment.
BIBLIOGRAPHY
- NCERT Chemistry Laboratory Manual Class XI.
- NCERT Chemistry Textbook Class XI.
- World Health Organization (WHO) Guidelines for Drinking Water Quality.
- Environmental Chemistry by A.K. De.
- Standard Methods for Examination of Water and Wastewater.
Comments
Post a Comment