Chem Com
1B11 – Water Testing Lab
Name ____________________
In this laboratory, you will use a method that chemists use to detect the presence of
specific ions in water solutions. Specifically, you will be testing tap water, fresh water,
ocean water, and well water for these four ions. To determine the presence of these ions,
you will be conducting tests called confirming tests. A Confirming Test is a test that
confirms that the ion in question is present. Two possible confirming tests are a change in
solution color, and/or the presence of a precipitate. A Precipitate is a solid that forms from
the chemical reaction of two aqueous solutions. If neither of these changes occur, then
either (1) the ion is not present, or (2) the ion is present in such small amounts, that it cannot
be detected. Both of these confirming tests are qualitative in nature. You will merely be
testing for the presence of the ion, not the amount of the ion present.
When conducting this experiment, you will need comparison data to determine your
laboratory results. First, you will need a Control, a sample that does not contain the ion,
which will be distilled water. Second, you will need a Reference, a sample that does
contain the ion, which will be labeled as such.
Then, you will test four water samples: tap water, fresh water, ocean water, and
well water. You will be looking for whether or not the water samples contain each of the
ions. The ions we will be testing for are: Calcium ions, Iron (+3) ions, Chloride ions, and
Sulfate ions.
MATERIALS:
Items:
Control:
Reference Solutions:
Test Solutions:
Confirming Solutions:
24-Well Microplate, Toothpick, White Paper, Q-tip,
Plastic Pipet
Distilled Water
0.1 M Iron (III) Nitrate
0.1 M Calcium Chloride
0.1 M Iron (II) Sulfate
Tap Water, Fresh Water, Ocean Water, Well Water
0.5 M Potassium Thiocyanate
0.1 M Sodium Carbonate
0.1 M Silver Nitrate
0.1 M Barium Chloride
*Helpful Hints*
Look for color changes against a white background.
Look for the presence of a precipitate against a black background.
Compare the two water samples against the control and reference samples
to aid in seeing very light color changes or precipitate formation.
PROCEDURE:
PART A: Calcium Test
1. Place 20 drops of Distilled Water to well A1.
2. Place 20 drops of Calcium Chloride (the reference) to well A2.
3. Place 20 drops of Tap Water to well A3.
4. Place 20 drops of Fresh Water to well A4.
5. Place 20 drops of Ocean Water to well A5.
6. Place 20 drops of Well Water to well A6.
7. Add three drops of Sodium Carbonate to each well (A1 to A6).
8. Record Results for each well. Record NR for no reaction. Be specific in your
description if any reaction happened.
PART B: Iron (+3) Test
1. Place 20 drops of Distilled Water to well B1.
2. Place 20 drops of Iron (III) Nitrate (the reference) to well B2.
3. Place 20 drops of Tap Water to well B3.
4. Place 20 drops of Fresh Water to well B4.
5. Place 20 drops of Ocean Water to well B5.
6. Place 20 drops of Well Water to well B6.
7. Add two drops of Potassium Thiocyanate to each well (B1 to B6).
8. Record Results for each well. See previous procedure for details about recording results.
PART C: Chloride Test
1. Place 20 drops of Distilled Water to well C1.
2. Place 20 drops of Calcium Chloride (the reference) to well C2.
3. Place 20 drops of Tap Water to well C3.
4. Place 20 drops of Fresh Water to well C4.
5. Place 20 drops of Ocean Water to well C5.
6. Place 20 drops of Well Water to well C6.
7. Add three drops of Silver Nitrate to each well (C1 to C6).
8. Record Results for each well. Record results properly.
PART D: Sulfate Test
1. Place 20 drops of Distilled Water to well D1.
2. Place 20 drops of Iron (II) Sulfate (the reference) to well D2.
3. Place 20 drops of Tap Water to well D3.
4. Place 20 drops of Fresh Water to well D4.
5. Place 20 drops of Ocean Water to well D5.
6. Place 20 drops of Well Water to well D6.
7. Add three drops of Barium Chloride to each well (D1 to D6).
8. Record Results for each well appropriately.
9. Empty and clean out your microplate with distilled water. Use a Q-tip to remove any
remaining debris as needed.
10. Clean up your laboratory area and wash your hands.
Chem Com
1B11 – Water Testing Lab
Name ____________________
Data Table:
Test
Control
Reference
Tap
Water
Fresh
Water
Sodium
Carbonate
Potassium
Thiocyanate
Silver
Nitrate
Barium
Chloride
ANALYSIS AND CONCLUSIONS:
1.
Were calcium ions present in the tap water?
Were they present in the fresh water?
Were they present in the ocean water?
Were they present in the well water?
________
________
________
________
2.
Were Iron (+3) ions present in the tap water?
Were they present in the fresh water?
Were they present in the ocean water?
Were they present in the well water?
________
________
________
________
3.
Were Chloride ions present in the tap water?
Were they present in the fresh water?
Were they present in the ocean water?
Were they present in the well water?
________
________
________
________
4.
Were Sulfate ions present in the tap water?
________
Ocean
Water
Well
Water
Were they present in the fresh water?
Were they present in the ocean water?
Were they present in the well water?
________
________
________
5. Why was a control used in each test? Why was that control distilled water?
6. Why were reference samples used in each test?
7. Under what conditions would you get a false negative result?
8. What did this laboratory tell you about the presence of ions in tap water, fresh water,
ocean water, and well water? Be specific and compare these types of water and their
ions.