Name
_________________________________
Conductivity of substances and Solutions Lab
Apparatus
Conductivity probes
Various substances (metals, molecular and ionic solids, liquids such as ethanol and vinegar)
100 mL beakers and distilled water
Pre-activity notes
Now that we have seen that various substance exhibit differences in the mobility of negative charge
in the atoms, perhaps we can use this to sort compounds. You can see for yourselves that metals are
conductors, but that the solids of compounds with metals do not conduct electricity. You will next examine
the electrical conductivity of solutions of these compounds to determine whether the solutions exhibit the
presence of charged particles. We can go on to further modify our atomic model of matter to account for our
observations.
Performance notes
Test samples of metals and compounds for electrical conductivity. You should test the dry solids
(where applicable) and then the solid mixed with water to produce about each solution in the test well. Test
the electrical conductivity of each solid and solution and record your findings; if possible, You should note
relative conductivity of the solutions. Be sure to wash off the electrodes thoroughly in between the test to
avoid contamination.
Table of electrical conductivity: (the 1st 2 rows are for the 2 metals)
If conducts- write if light was dim(or beeps softly), this is a weak electrolyte or blinks (or beeps loudly)
this is a strong electrolyte.
If no conduction – write “none” (nonelectrolyte)
Name & formula of substances
Phase @ room
Conductivity of Solution
Conductivity
temperature
made from solid compound
As solid compound
XXXXXXXXXXX
XXXXXXXXXXX
Isopropyl Alcohol (C3H7OH)
(rubbing alcohol)
XXXXXXXXXXX
Vinegar (acetic acid)
(CH3COOH or HC2H3O2)
XXXXXXXXXXX
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Conclusion: READ THIS CAREFULLY!!!!
Use conductivity to sort the compounds into electrolytes and non-electrolytes.
We observe two types of behavior among compounds. One type of substances does NOT conduct electricity
either as a solid or as a liquid. We model these substances as being composed of neutral aggregates of atoms
we call molecules (molecular compounds). This behavior is typical of compounds of non-metals, but there
are exceptions.
The other type of substance does not conduct as a solid, but does when dissolved. We can model these as
dissolving into oppositely charge particles we call ions that can move freely in solution. The presence of an
electric field causes these charged particles to migrate (or move around) resulting in an electrical current,
(ionic compounds).
1. Using your observations, define the following:
electrolytes:
weak electrolyte:
strong electrolyte:
nonelectrolyte:
2. Using your definitions above and your observations from your lab, classify all the SOLUTIONS (THE
SOLIDS DISSOLVED IN WATER AND ALL THE LIQUIDS EXCEPT WATER), AND THE
SOLUTIONS ONLY, under the proper heading. Just put check marks under the proper headings for each
compound. Only evaluate the compounds in the solution column of your results from page 1.
DO NOT EVALUATE ANY SOLIDS OR WATER!
DO NOT EVALUATE THE 2 ELEMENTS: ______________, ________________
(Don’t write these in this table!!!!!)
Compound
(name and chemical formula)
weak electrolyte
2
strong electrolyte
nonelectrolyte
3. Did any solids, other than the metals, conduct electricity?
4. When these same solids (from #3) were dissolved in water (made into solutions), did they conduct
electricity (these are electrolytes)?
5. List these compounds. Put their name and chemical formula.
6. Circle the 1st element, and the 1st element only, of the compounds you just listed in #5. Write those
elements here; name and chemical symbol. Find each of these elements on your periodic table. Using your
periodic table as a tool to determine whether the element is a metal or nonmetal, next to each element write
“metal or nonmetal”.
7. READ the 2nd paragraph on p. 2 carefully. What are these compounds called? WHY can these
compounds conduct electricity in solution form?
8. Draw a particle diagram of the solid form of this type of compound, choose any one of them, AND a
particle diagram of what you believe the compound looks like after it is dissolved in water (solution form).
9. Write at least 2 physical properties (NOT HOW THEY ARE NAMED!!!) of these types of compounds.
10. Now, list all the compounds that did not conduct electricity (nonelectrolytes) whether they were in liquid
or solid form? List by name AND chemical formulas.
11. From the compounds in #10, list each element and its name separately. Find these elements on the
periodic table. Which category do all these elements fall under; metals or nonmetals?
12. Carefully READ the 1st paragraph on p. 2. What is the name of this category of the compounds listed in
#10?
13. List at least 2 physical properties of these compounds. (DO NOT SAY ANYTHING ABOUT THEIR
NAMES)
14. There is one compound that is an electrolyte BUT is made up of all nonmetals. What compound is that?
This category of compounds is what we call “an exception to the rule”. We will get to this category in the
very near future….stay tuned.
15. Under each heading, make a summary of your findings for Ionic Compounds and Molecular compounds.
List at least 3 physical properties for each type of compound. DO NOT SAY ANYTHING ABOUT NAMES
OR NAMING!!!
IONIC COMPOUNDS
MOLECULAR COMPOUNDS
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16. Using what is written under "conclusion", your definitions for #1 and 3, and your observations from
your data, classify all the compounds (NOT the elements), into their proper categories. Write the compound
in the 1st column then check the 2 categories that the compound fits under. There is an example compound
completed for you.
*What are the 2 elements used in this lab? ________________, _________________
DO NOT classify these.
**ALL compounds will go under TWO (2) categories.
Compound
Electrolyte
Ionic compound
(name and symbol)
Zinc chloride
x
Nonelectrolyte
Molecular
compound
x
17. Now that you have filled in this table you should be able to fill in another property for ionic compounds
and molecular compounds. What general conclusion can you make about the conductivity of ionic and
molecular compounds? Also put this conclusion in the table in question #15.
18. In your notebooks, write the heading “Conductivity Lab: Ionic and Molecular Compounds”.
* We will be discussing the contents of this lab in class.
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