IONIC OR COVALENT LAB
The type of bonds that hold their atoms together can classify compounds. Ions are held
together by ionic bonds in ionic compounds. Atoms are held together by covalent
bonds in molecular compounds.
You cannot tell if a compound is ionic or covalent simply by looking at a sample of it
because both types of compounds can look similar. However, simple tests can be done to
classify compounds by type because each type has a set of characteristic properties
shared by most members. Ionic compounds are usually hard, brittle, water or alcohol
soluble, have high melting points and can conduct electricity. Covalent compounds can
be soft, hard or flexible, are usually less water-soluble (or alcohol soluble), have lower
melting points and cannot conduct electricity when dissolved in water.
PU RP OSE : Learn how to identify ionic and covalent compounds.
R ESE A R C H :
1. Describe the difference between ionic and covalent bonding in terms of electrons.
2. Describe why ionic compound bonds are more difficult to break than molecular
covalent bonds.
H Y P O T H ESIS: You are on your own here. 5HPHPEHUWRZULWHDQ³LI´«³WKHQ´«
statement.
M A T E R I A LS:
1. Spot plate
2. Hot plate
3. Conductivity Tester
4. Alcohol
5. Aluminum foil square
6. Mortar and pestle
7. Scoopula
8. CaCl2
9. KI
10. C13H18O2 (ibuprofen)
11. C8H9NO2 (acetaminophen)
12. C12H22O11 (maltose)
PR O C E D U R E :
1. Make a chart with the following seven headers: Substance, Hardness, Melts or
not, Dissolves in water, Dissolves in alcohol, Conducts electricity when in water
solution, and Ionic or Covalent for the last column.
2. Feel a small sample of each substance and record on your chart whether it is hard,
brittle or soft. Save this sample on a paper towel to use in Part 1.
Part 1
3. Get a square of aluminum foil and draw six (6) wedge shapes on it. Label the
wedges A, B, C, D, E and F.
4. Place a SMALL sample of each substance in the appropriate wedge of your foil.
5. Place the foil on a hot plate and turn it on high.
6. After a few minutes, observe each section and record on a chart, which substances
have melted and their order.
7. Turn off the hot plate.
Part 2
8. Label six (6) spot plate wells with the letters of the substances.
9. Place a SMALL sample of each substance in the appropriate spot plate well.
10. Fill each well with water from the sink and stir.
11. Repeat procedure with all six substances using alcohol on the another row.
12. Record whether substance dissolved or not on your chart.
Part 3
13. This part will be done as a class demonstration.
14. Lab group 1 will make a solution of substance A, group 2 of substance B, group 3
of substance C, group 4 of substance D, group 5 of substance E, group 6 of
substance F.
15. Fill a 100 mL beaker with 60 mL of water. Dissolve a small amount of your
assigned substance into the beaker.
A N A L YSIS Q U EST I O NS:
1. Use your melting point data to explain the relative strengths of ionic and
molecular covalent bonds.
2. Will the melting point of an ionic compound most likely be higher or lower
when the bond is stronger? What determines the strength of an ionic bond?
(HINT: Will the charge be higher or lower? Will the ion be larger or
smaller?)
3. Look at the halogen family on the periodic table of elements. Note fluorine
and chlorine are gases, bromine is a liquid and iodine is a solid. Every
halogen forms a molecular covalent bond with itself. Ex. F2, Cl2, Br2, and I2.
Using the above trend information, what can you conclude occurs as the
number of electrons increases when molecular bonds are formed?
4. Considering the above information, would glucose (C6H12O6) or maltose
(C12H22O11) have a higher melting point? Justify your answer.
'21¶7IRUJHWWRZULte a conclusion! Write at least three sentences plus answer questions
on lab rubric.