Testing the
Waters
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2: Chemical Testing for Chlorine Iron, Sulfide, and Dissolved Oxygen
What is in the water, besides all those molecules of H2O? To answer this question, you will need to do some chemistry! In this lesson, you will be running chemical tests of water quality on your local drinking water and water collected from a nearby stream, river or lake. As you study the quality of this water, you will probably want to further consider the water quality standards and the causes of certain pollutants. We will be comparing our results with those of our partners across the globe and will be making some decisions about which water characteristics we may want to continue to monitor throughout the remainder of the school year.
Objectives
In this activity you will...
- use test kits to measure the level of chlorine, iron, sulfide, and dissolved oxygen in tap (drinking) water and stream water.
- post and evaluate the results of these water quality tests.
- make conclusions about whether the water needs to be cleaned or regularly monitored for these characteristics.
Materials
- chlorine test kit
- iron test kit
- sulfide test kit
- dissolved oxygen test kit
- samples of water, taken from the water source of a local stream, river or lake
- samples of water, taken from students' homes or school water fountain
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Invitation
Your teacher will review your activities from lesson one. Now it is time for you to be introduced to the water testing kits. Your teacher will explain how the various tests are conducted. Give careful attention to the discussion on accurate readings of the chemical tests. You may want to visit the Chemetrics website to read about test kits.
Before conducting the tests, predict whether you anticipate any water quality problems. In other words, do you expect your water to be within or outside of the acceptable range for chlorine, iron, sulfide, and dissolved oxygen?
1. Before we
test our water, let's take a look at these four water
quality characteristics.
Investigate each
of the links below. Consider what each characteristic
teaches us about water quality. Write down the acceptable
range or "satisfactory level" of each.
2. Based on the information you have found, predict the level of each characteristic for the tap water and outdoor water sample that you will be testing. Discuss this with your classmates and write down what you expect.
3. Now it's time to test water for each of the four indicators. Each group of 3-4 students will be given water testing materials for chlorine, iron, sulfide, and dissolved oxygen. You will be testing two water samples: drinking water and your outdoor water sample.
You should test both water samples, register results, and discuss them in your groups.
4. Your
teacher will draw a data table in which each group will
write their results for the water tests. From this group
data, calculate class averages for each of the four tests,
and post the class results on the Eco-Connections
Project Forum.
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chlorine |
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iron |
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sulfide |
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dissolved oxygen |
How do your results compare to your predictions? What have you learned about your drinking water, and your outdoor water sample?
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Explanation
After sharing your
results on the Eco-Connections
Project Forum,
compare what you found with the results of your partners
across the globe. Compare and contrast the results found in
Russia and the United States. How are the results similar?
How do the results differ?
Write a summary of the class results, including the comparison with the other groups. Post your conclusions and final thoughts on the Eco-Connections Project Forum for other students to read. Do any of the results raise concern water quality? Discuss whether the water source needs to be cleaned or regularly monitored for certain pollutants.
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Conclusion
You
have learned about four of the chemical indicators of water
quality. These are just some of the chemicals in water,
besides H2O. In our next lesson, we will
measure four other indicators.