BOND TYPES AND PHYSICAL PROPERTIES
Introduction:
The type of bond present in a compound will determine the general physical properties of
that compound. In this experiment the properties of solubility and melting point will be compared for typical ionic and covalent compounds.
Purpose:
To compare the properties of solubility, conductivity, and melting point for ionic
and covalent compounds.
Equipment/Materials:
Small test tubes (10 per group)
Test tube rack or 24-well plate
Mel-temp/thermometer (set at 200oC)
Capillary tubes
Water (polar solvent)
Iso-butanol (nonpolar solvent)
Conductivity testers
Safety:


sodium chloride
magnesium sulfate
stearic acid
vanillin
cooking oil
parafilm
Always wear safety glasses in the lab.
The Mel-temp can become very hot. Avoid touching the metal surfaces.
Procedure:
1. Obtain ten (10) small test tubes and label two each with the identity of each solid to be tested
and the cooking oil. Next to the name of each compound on one set of tubes, place a “W”.
2. Fill the set of 5 tubes that are marked with the “W” 1/3 to 1/2 full of deionized water (very
polar solvent).
3. Fill the other set of 5 test tubes 1/3 to 1/2 full of iso-butanol (nonpolar or very slightly polar).
4. Place a very small sample of each solid (enough to fill up this circle O) into each tube labeled
for that solid (2 test tubes each). (NOTE: Do NOT use much of the solid. If too much
solid is used, even those that are soluble will be present in too high a concentration to go
completely into solution. This will yield erroneous results.) Place a few drops of cooking
oil into those two properly labeled test tubes.
5. Mix the contents of the test tubes well by placing a small piece of parafilm over the top of
each tube and shaking. Record your observations regarding the solubility of each of the
substances in each solvent.
6. For each compound that was soluble in water, pour some of that mixture from the test tube
into a well on a 24-well plate. Test the wells with a conductivity tester by placing both
prongs of the testers into the mixture and pressing the button on the side of the tester. Record
the number displayed in the data table.
7. Place a sample of each of the solid substances in a melting point capillary tube. Mel-temps
will be preset to 200oC.
8. Only three capillary tubes can be placed into a Mel-temp at one time. Pay attention to which
sample is placed into which well of the Mel-temp so that you will know how to record your
results. Allow the capillaries to stay in the Mel-temp for 3 minutes. At the end of the 3
minutes, observe the tubes to see if any have melted.
9. Record the melting point as “low” (below 200oC) if the solid has melted. Record the melting
point as “high” (above 200oC) if the solid has not melted.
10. Identify the types of bonds present in each of the solids based upon its solubility and melting
point.
BOND TYPES AND PHYSICAL PROPERTIES
Data Table
Name(s):
Date:
Period/Lab Group:
Data Table:
Substance
Solubility in Solubility in
Water
Iso-butanol
(“S” or “N”) (“S” or “N”)
If soluble in
water, check
conductivity
(record number)
Sodium
chloride
Magnesium
sulfate
Stearic acid
Vanillin
Cooking oil
Questions:
1. What are two general properties of ionic compounds?
2. What are two general properties of covalent compounds?
Melting
Point
(low or
high)
Type of Compound
(ionic, polar covalent,
or nonpolar covalent)