YIELD OF A CHEMICAL REACTION
Be sure your Prelab question answers have been checked by your lab instructor.
Use analytical balance throughout this experiment.
Use one of the following Groups based on the last digit of your student ID#, as shown
below, to record all of your data:
Last Digit of ID#:
0 through 4
5 through 9
1) Weigh a dry crucible and lid at room temperature (cold like the glassware in your drawer).
If you rinsed your crucible, you must heat it
with a Bunsen burner, and allow it to
(If you heat it too quickly, it will cause the crucible to crack.
The crack may not be
evident until later in the experiment, and result in your having to repeat the experiment).
Does your crucible have a black stain inside?
2) From the front reagent shelf, obtain approximately 0.12 – 0.15 g of Mg turnings.
3) Measure and record the mass of the crucible, lid and magnesium.
4) Place the crucible, lid and Mg in a clay triangle on an iron ring so that the bottom of the
crucible will be about 1 cm above the inner blue cone of the Bunsen burner flame.
the center of the flame towards the front edge of the bottom of the crucible, and using your
crucible tongs, hold up the front edge of the lid so that you can watch the Mg.
5) Heat the crucible very strongly until the Mg begins burning (flame or bright light).
burning begins, remove the burner (to remove the major source of CO
and CO) and keep
the Mg burning by opening the lid a little more (to allow more oxygen in, and nitrogen out)
when the reaction slows.
begins to escape, lower the lid momentarily to
decrease the supply of oxygen and to avoid loss of the white smoke (which is small
particles of your product).
Keep the opening just small enough to keep the smoke from
escaping, but large enough to maintain burning.
As soon as it seems to stop burning,
remove the lid.
If it begins to burn rapidly and emit smoke, lower the lid to control product