Stoichiometry Lab
Materials needed
Strontium chloride
potassium sulfate
150 mL beaker
balance
stirring rod
ceramic dish
150 mL Erlenmeyer flask
funnel
wash bottle
11 cm filter paper
Check for sodium or potassium sulfate
chemical scoop
weighing boat
ceramic triangle
ring stand with ring
distilled water
Waste container
Summary:
This lab is designed to test the students’ to abilities to perform stoichiometric calculations and laboratory
separation. A prerequisite lab to separate sand from either salt or sugar may be necessary to acquaint the
student with separation by filtration. This lab should be done over a period of three days, however steps 1 and 2
can be combined into one class period. The actual filtration is a slow process. The third step should be done on
a Friday to allow the filtrate to dry over the weekend. At the very least, it should dry for 2 days. This is to
make sure that we are not including water when we mass our product.
Phase 1:
1. Calculate how many grams of strontium chloride are required to produce 5.0 grams of strontium sulfate.
This is your required amount of strontium chloride.
2. Calculate how many grams of potassium sulfate are required to produce 5.0 grams of strontium sulfate.
This is your required amount of potassium sulfate
3. Have your instructor check your results before continuing.
4. Mass out your required amount of strontium chloride in a weighing boat. Carefully pour it into your 150
mL Erlenmeyer Flask.
5. Mass out your required amount of potassium sulfate in a separate weighing boat. Carefully pour it into
your 150 mL beaker.
Phase 2a:
1. Assemble your filtration apparatus
2. Record the mass of the filter paper.
3. Put a ceramic triangle on the ring if needed to support the funnel
4. Fold the filter paper in half and then in half again as demonstrated. This forms your filter funnel.
5. Put the filter funnel into your funnel. Wetting it may help it to stay in place properly.
6. Use a beaker for your waste container underneath the funnel. Make sure it is big enough to hold the
water you’ll pour through the filter.
Phase 2b:
1. Dissolve the potassium sulfate into about 75 mL of water in your beaker. Use your stirring rod.
2. Dissolve the strontium chloride into about 40 mL of water in your Erlenmeyer flask. Swirl your flask.
3. Pour your strontium chloride into your beaker of potassium sulfate.
4. Use your wash bottle to rinse all the strontium chloride out of your flask into the beaker.
Phase 2c:
1. Pour the mixture slowly into your filtering funnel.
2. Use your wash bottle to rinse any product out of your mixing beaker.
3. If any product shows up in the filtered water, stop and try to determine the cause and correct it before
continuing. Note: Do not punch a hole in your filter paper
4. When all of your mixture has been filtered through, remove the filter paper from the funnel and set it in
a ceramic dish to dry.
Phase 3:
1. Mass the filter paper with the product in it.
2. Determine the mass of the product in the filter paper.
3. Calculate the percent yield.
Summary questions
1.
Why was it necessary to make sure your filter paper was dry before you made your final
measurement?
2.
If you did not achieve 100% recovery, offer an explanation as to why?
3.
Why do you think we did not make our final product in the flask?
Stoichiometry results and grade sheet
Names: _______________________________________________
SrCl2 + K2SO4  SrSO4 + KCl
Show work here:
A.
Amount of strontium chloride required: ___________________
B.
Amount of potassium sulfate required: ____________________
C.
Dry mass of filter paper: _____________________
D.
Mass of filter paper and product from Phase 3: ______________
E.
Mass of product recovered (D-C): ______________
F.
Percent yield: _________________
Questions:
1. ._________________________________________________________________________________
2. ._________________________________________________________________________________
3. ._________________________________________________________________________________
Grade Sheet
Calculations
20
______
Procedure
30
______
Neatness
20
______
Final results
20
______
Questions
10
______
Project Grade 100
______ Counts as two (2) lab grades