Stoichiometry Lab
Purpose:
Materials needed:
test tube
balance
goggles
test tube holder
Bunsen burner
apron
gloves
scrub brush
Chemicals needed:
Hydrochloric acid ( HCl ) - 5 to 10 ml
WARNING: acid -do not expose to skin or breath fumes. If you spill acid on
you or your clothes, wash and inform the teacher immediately.
Magnesium ( Mg )
- approximately 0.3 g to 0.5 g
Procedure:
Before you start the experiment be sure to wear goggles, apron, and gloves
through out the experiment.
1. Clean and dry the test tube using the Bunsen burner. The test tube holder and
gloves should be used for this step.
2. Mass the dry test tube.
3. Mass an amount of magnesium some where between 0.25 g and 0.45 g
4. Carefully fill the test tube about one third of the way full with hydrochloric
acid using your dropper.
5. Slowly add the magnesium to the acid. Add only a few pieces at a time. Be
careful not to let the reaction over flow. This reaction is also exothermic so it
will get very hot.
6. After adding all of the magnesium wait until it has completely dissolved.
7. There is now magnesium chloride in the acid. The next step is to slowly boil
away the acid so that the magnesium chloride will be left behind.
8. Using the Bunsen burner boil away all of the acid. Be sure to heat the solution
slowly or it will froth. This will cause your calculations to be wrong.
9. Mass the magnesium chloride in the test tube.
10. Clean up, inform the teacher, and complete calculations.
DATA SHEET
Experimental Data:
1. Mass of test tube (after heating)
____________
2. Mass of magnesium
____________
3. Mass of magnesium chloride and test tube ____________
4. Mass of magnesium chloride produced (3-1)____________
Observations:
Description of magnesium -
Description of hydrochloric acid -
Description of magnesium chloride -
Description of reaction -
Theoretical Data:
1. Balanced reaction
2. Calculation of the mass of Magnesium chloride that will be
produced.
3. Calculation of the mass of hydrogen released into the air.
Comparison of Experimental and Theoretical:
| Theoretical mass - Experimental mass |
percentage error = ------------------------------------------ X 100
Theoretical mass