SNC 2D
Name: ___________________
(develop a title for this experiment)
Introduction
Water in its natural form is almost never pure H2O. In fact, most water contains many other dissolved
substances.
When an ionic compound is added to water, it will separate into its ions. For example, when sodium
chloride (NaCl) is added to water it will separate into Na1+ and Cl1- ions.
Well water that comes from the ground will contain many of the dissolved ionic compounds that are
found in the ground. These ions include positive ions like calcium (Ca2+), magnesium (Mg2+), and iron
(Fe3+), and negative ions such as chloride (Cl1-), nitrate ((NO3)1-) and sulphate ((SO4)2-).
Since ions are not usually visible, chemical tests are used to detect and identify ions in water. Most
chemical tests involve mixing two solutions that produce an insoluble solid (precipitate). A positive test
is one that clearly indicates the presence of the ion. A positive test may produce a precipitate, colour
change or both.
In this investigation, you test for the iron ion(Fe3+), chloride ion (Cl-), and sulphate ion(SO4)2-) ions
dissolved in three different water samples and one unknown sample solution.
Purpose:____________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
Hypothesis: It was believed that the:
Materials:
Procedure
Part 1
1. Complete the title, impersonal purpose, hypothesis (what ions do you expect in the distilled water,
tap water, and well water and unknown sample?), and materials section for your report.
2. Examine the three sample solutions and the three testing solutions. Write down three physical
properties for each and fill in observation table 1.
3. Add two drops of tester solutions to two drops of each of the sample solutions. Record your
observations particularly any changes in colour or formation of precipitate in table 2.
Part 2
1. Place two drops of each water sample into three different spots on your tray. Observe the sample
of water and record observations in table 2.
2. Add 1 drop of tester solution to each of the water samples. Record your results table 3.
3. Repeat for other two tester solutions in new water samples. Record your results in the provided
table.
Observations Part 1: (Complete the following tables including observations of all reactants and products)
Table 1: Physical Properties of the Solutions
Sample
3 Physical Properties
Table 2: Identifying Positive Tests for Ions
Silver (I) nitrate
Testers and formulas
Barium chloride
→
Positive Samples
Potassium
thiocyanate
RESULTS
Potassium Chloride
Sodium sulphate
Iron (III) nitrate
Conclusion part 1:
1) Silver nitrate tests for ________________________________ ions.
2) Barium chloride test for _______________________________ ions.
3) Potassium thiocyanate tests for ________________________ ions.
Observations Part 2
Table 3: Testing for Ions in Water Samples
Testers
--->
Samples
Silver nitrate
Barium chloride
Potassium thiocyanate
Distilled Water
Well Water
Tap Water
Unknown
Conclusion: answer the following questions with complete sentences on your own paper.
1. What is meant by a “positive” test for an ion?
2. Write the chemical formulas for silver nitrate, sodium sulphate, barium chloride and
iron (III) nitrate.
3. How could you tell how much sulphate was present in two different solutions by adding
barium chloride?
4. List any problems that you had when following the procedure or doing the experiment.
Suggest what could be done to improve the experiment.
5. State which ions were found in each of the 3 water samples and the unknown sample.
What was your proof for each sample?
6. Where might your unknown sample come from (read introduction)? Explain your answer.