Lab provided by Ms. Beaton (http://home.earthlink.net/~ssbeaton/index.html)
though I have modified it.
In this lab you will determine the empirical formula of the compound
magnesium oxide. The compound will be made by burning magnesium ribbon in
air. In addition, you will be learning to collect and record your own data.
No data tables have been provided so you will have to create your own.
Also, be sure that at least one lab partner is keeping notes on the
procedure so that any errors or problems can be included in the report. Materials
1. ring stand 4. gas burner 7. magnesium ribbon
2. ring 5. crucible with lid 8. balance
3. clay triangle 6. tongs 9. safety goggles Procedure
Set up the ring stand with the ring. Place the clay triangle on the
ring. Place the burner under the clay triangle.
Clean a crucible and lid with water. Heat them to dry, then continue
heating for 5 minutes.
Allow to cool for 5 minutes. For the rest of the lab, use the tongs to
handle the crucible, do not touch with your hands.
Mass the crucible and lid. Record.
Place a coiled 25 cm length of magnesium ribbon in the crucible. Mass
the crucible, lid, and Mg. Record.
Do not look directly at the magnesium burning. Over a high flame, heat
the uncovered crucible until the magnesium ignites. As soon as it is
burning, place the cover over the crucible and remove the burner. This
After smoke production has ceased, replace the burner and continue
heating the crucible.
Every 2-3 minutes, carefully lift the lid and check the reaction. After
heating a total of 10 minutes, check to see that the reaction is
The magnesium should be completely converted to a white/light grey
powder. If ribbonlike material remains, continue heating until it is
Turn off the burner. Allow the crucible to cool completely (at least 7
Mass the crucible, lid and magnesium oxide. Record.
The solid can be disposed of in the trash. Wash out the crucible and
put away the materials.
Notes on the procedure: If the crucible lid is not put on right away
when the magnesium starts to smoke, product can be lost. Also, if a
green-yellow solid is forming, too high of a temperature is being used and
magnesium nitride may be forming. Needless to say, this is bad. Discussion
Write a lab report on a separate piece of paper and be sure to create and
include a neat, readable data table. Keep this lab packet for future
reference. The lab report should include the following sections:
Abstract: Briefly (50 words or fewer) state the purpose and
findings of the lab. Materials: Write a list of the materials used in the lab. Procedure: Write the procedure given in your own words. Data: You will collect two kinds of data: qualitative and
quantitative. The qualitative data include your own impressions and
observations about the experiment and may include pictures. The
quantitative data are the data you were told to collect in the procedure.
Also include any other numerical data that is relevant. Data Analysis: Calculate the empirical formula for magnesium
oxide using your data. Show all work clearly. Error Analysis: be sure to mention how possible errors may affect
results. Conclusion: Briefly state your results. No new information should
be introduced here.