Experiment 2.1
Water Testing (4)
Lab Report = 67
(5) Introduction:
Chemists can detect and identify ions in water
solution in several different ways. In this activity
you will use some chemical tests to check for
the presence of certain ions in aqueous solution.
Positively charged ions have a deficiency of
electrons and are called cations; negatively
charged ions have an excess of electrons are
called anions. You will investigate two cations
and two anions.
The tests you will perform are confirming tests
(qualitative analysis). That is, if the test is
positive it confirms that the ion in question is
present. In each confirming test you will look for
a change in solution color or the appearance of
an insoluble material called a precipitate. A
negative test (no color or precipitate) doesn’t
necessarily mean the ion in question is not
present. The ion may simply be present but in
such a small amount that the color or precipitate
cannot be seen.
You will test for the presence of the cations
iron(III), Fe3+, and calcium, Ca2+, as well as the
anions chloride, Cl-, and sulfate, SO42-.
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(2) Objectives:
1. Check for the presence of certain ions in
water sources
3. Qualitative analysis of ions
4. Using pH sensor to record pH of water
sources.
2. Observe chemical reactions
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Apparatus:
Well-plate
safety glasses or goggles
laboratory apron
Logger Pro pH sensor
50 mL beaker
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(5) Reagents:
Deionized water
Tap water
Water from foul water lab
Natural water source
0.1 M calcium chloride (CaCl2)
1.0 M sodium carbonate (Na2CO3)
0.1 M iron(III) chloride (FeCl3)
1.0 M sodium sulfate (Na2SO4)
0.1 M potassium thiocyanate (KSCN)
0.1 M sodium chloride (NaCl)
0.1 M silver nitrate (AgNO3)
0.1 M barium chloride (BaCl2)
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Procedure:
1. Adorn your safety glasses and lab apron.
2. The test procedure for each ion are given below.
If the ion of interest is present, a chemical
reaction will occur (color change or ppt). The
chemical equations involved are given for each
ion.
4. Place each sample into a well plate to about half
full. Use the larger wells.
a. 0.1 M Calcium Chloride (CaCl2) [reference]
b. Water samples (deionized water, tap water,
cleaned foul water and natural water source)
3. Obtain about 50 mL of each water source
(Deionized water, tap water, cleaned foul
water, and natural water source)
5. Add three drops of 1.0 M sodium carbonate
(Na2CO3) to each well.
Calcium Ion Test (Ca2+)
Ca2+(aq)
+ CO32-(aq) 
CaCO3(s)
calcium ion
carbonate ion
calcium carbonate
6. Record your observations including the color and
whether or not a precipitate formed. Get
Stamp!
Experiment 3-1
Page 1
7. Discard all solutions down the sink with water.
Iron(III) Ion Test (Fe3+)
Fe3+(aq) + SCN-(aq)  [FeSCN]2+(aq)
Iron(III) ion thiocyanate ion iron(III) thiocyanate
(red color)
8. Place each sample into a well plate to about half
full. Use the larger wells.
a. 0.1 M Iron(III) Chloride (FeCl3) [reference]
b. Water samples (deionized water, tap water,
cleaned foul water and natural water source)
9. Add three drops of 0.1 M potassium thiocyanate
(KSCN) to each well.
10. Record your observations including the color
and whether or not a precipitate formed. Get
Stamp!
11. Discard all solutions down the sink with water.
Chloride Ion Test (Cl-)
Cl-1(aq) + Ag+1(aq)  AgCl(s)
Chloride ion Silver ion
Silver Chloride
12. Place each sample into a well plate to about
half full. Use the larger wells.
a. 0.1 M Sodium Chloride (NaCl) [reference]
b. Water samples (dionized water, tap water,
cleaned foul water and natural water source)
14. Record your observations including the color
and whether or not a precipitate formed. Get
Stamp!
15. Discard all solutions down the sink with water.
Sulfate Ion Test (SO42-)
Ba2+(aq) + SO42-(aq)  BaSO4(s)
Barium ion
Sulfate ion
Barium Sulfate
16. Place each sample into a well plate to about
half full. Use the larger wells.
a. 1.0 M Sodium Sulfate (Na2SO4) [reference]
b. Water samples (dionized water, tap water,
cleaned foul water and natural water source)
17. Add three drops of 0.1 M barium chloride
(BaCl2) to each well.
18. Record your observations including the color
and whether or not a precipitate formed. Get
Stamp!
19. Discard all solutions down the sink with water.
pH Testing
20. Obtain samples of each water source including
DI water.
21. Add about 15-20 mL of each water sample to a
50 mL beaker and determine the pH of the water
using Logger Pro pH sensor as performed in
Experiment 1.1. Record the pH of each.
22. Clean the sensor after each testing.
13. Add three drops of 0.1 M silver nitrate (AgNO3)
to each well.
23. Clean up all materials and wash your hands
thoroughly.
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Data and Observations: (25)
Data Table
Calcium (Ca2+)
Reference
DI water
Tap water
Cleaned Foul Water
Natural Source
Stamp! (5)
Experiment 3-1
Observations (color/ppt)
Result (Is ion present?)
Page 2
Iron(III) (Fe3+)
Reference
DI water
Tap water
Cleaned Foul Water
Natural Source
Stamp! (5)
Chloride (Cl-)
Reference
DI water
Tap water
Cleaned Foul Water
Natural Source
Stamp! (5)
Sulfate (SO42-)
Reference
DI water
Tap water
Cleaned Foul Water
Natural Source
Stamp! (5)
Water Sample
DI water
Tap water
Cleaned Foul Water
Natural Source
Stamp! (5)
Observations (color/ppt)
Result (Is ion present?)
Observations (color/ppt)
Result (Is ion present?)
Observations (color/ppt)
Result (Is ion present?)
pH
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(14) Analysis and Conclusions:
(2) 1. Why was deionized water used in each test?
(4) 2. Describe some difficulties associated with the
use of qualitative tests.
(4) 3. These tests cannot absolutely confirm the
absence of an ion. Why?
(4) 4. How might your observations have changed if
you had not cleaned your well plate thoroughly
between each test?
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(12) Synthesis:
(4) 1. Develop a hypothesis on why would
chlorides be present in tap water?
(4) Is pH a good indicator of “clean” water? Explain.
(4) 2. Develop a hypothesis on why would calcium
be present in natural water source?
Experiment 3-1
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