SCH4C
Stoichiometry Design Lab
Strontium and Copper (II)
Name:
In chemical reactions, the actual masses of substances used are proportional to their molar
masses. Therefore it is possible to predict the number of grams of a given product that will be
formed in a reaction if you know the mass of any one of the reactants. Stoichiometry can be used
be used to determine the mass of the precipitate produced by a reaction between aquaeous
strontium chloride hexahydrate and aquaeous copper (II) sulfate pentahydrate
Your Task: in this lab, you will start with a known mass of strontium chloride
hexahydrate and a known mass of copper (II) sulfate pentahydrate. You will
calculate the moles of each substance and then determine the theoretical mass
of the precipitate that should be formed. Once the procedure is complete, you
will mass the actual precipitate formed. The difference between the actual yield
and the calculated (theoretical) yield can then be used to determine the percent
yield of your product.
Purpose:
 To write and balance an equation with states included
 To calculate the theoretical yield of a reaction
 To mass the actual mass of a reaction
 To compare the actual mass to the theoretical mass and determine
percent yield.
Materials:
 Eye protection
 Scoopula
 2.00 g strontium chloride
hexahydrate
 2.00 g copper (II) sulfate
pentahydrate
 75 mL water
 Graduated cylinder
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2-250 mL beakers
Filter paper
Funnel
Ring
Ring stand
Digital scale
Procedure:
1. Mass 2.000 g strontium chloride hexahydrate into a 250 mL beaker
2. Mass 2.000 g copper (II) sulfate pentahydrate into a 250 mL beaker
3. Measure 35 mL water using a graduated cylinder and pour into copper (II)
sulfate pentahydrate. Stir.
4. Measure 40 mL water using a graduated cylinder and pour into strontium
chloride hexahydrate. Stir.
5. Combine the two aqueous solutions into one beaker.
6. Mass the filter paper. Fold a filter paper as instructed and place it into the
funnel. Set the ring stand, ring with funnel over the empty beaker.
7. Filter the precipitate. Make sure to rinse empty beaker into filter paper to
capture all PPT. Let the precipitate dry. Clean up equipment and station.
8. Mass the dry precipitate and filter paper.
SCH4C
Stoichiometry Design Lab
Strontium and Copper (II)
Observations:
Table 1: Qualitative Observations
Copper (II)
Strontium
Mixture of
Sulfate
Chloride
both solutions
pentahydrate
hexahydrate
(s)
(s)
Table 2: Quantitative Observations
Mass Copper (II)
Mass Strontium
Sulfate
Chloride
pentahydrate (g)
hexahydrate (g)
Volume of Water
(mL)
Name:
Precipitate (s)
Mass of filter
paper (g)
Dry PPT on
filter paper
Mass of filter
paper and dry ppt
(g)
Volume of Water
(mL)
Balanced Equation:
Strontium chloride hexahydrate reacts with copper (II) sulfate pentahydrate to
produce strontium sulfate as a precipitate. The other product is copper (II)
chloride, which remains in solution.
Calculations:
1. Molar mass Copper II Sulfate pentahydrate
2. Moles Copper II Sulfate pentahydrate
SCH4C
Stoichiometry Design Lab
Strontium and Copper (II)
Name:
3. Molar Mass Strontium Chloride hexahydrate
4. Moles Strontium Chloride hexahydrate
Analysis:
5. Mole ratio (based on balanced equation) between Copper Sulfate and
Strontium Chloride
6. Use mole ratio and one of the answers in 2 or 4 to determine the limiting
reactant.
7. Mole ratio between limiting reactant and PPT (based on balanced
equation)
8. Use mole ratio of limiting reactant and PPT with the moles determined in
step 2 or 4.
9. Convert moles to grams using the molar mass of PPT. (This is theoretical
yield, you calculated what you should get)
10. Mass of the PPT (This is your actual yield)
11. Percent yield = actual yield / theoretical yield x 100%
SCH4C
Stoichiometry Design Lab
Strontium and Copper (II)
Name:
Discussion:
Copper II ions dissolve in solution generally appear as a pale blue colour. Why is
the colour of the final reaction NOT a good indication of which reactant is the
limiting reactant?
Is it possible to achieve more than 100% yield? Explain.
What are some reasons why the theoretical yield is not the same as the actual
yield?
Sources of Error:
INCLUDE: percentage error calculation.
actual  theoretical
 100
% error =
theorectical
SCH4C
Stoichiometry Design Lab
Strontium and Copper (II)
Name:
Expectations
E2. investigate chemical compounds and chemical reactions using appropriate
techniques of quantitative analysis, and solve related problems;  E2.1 use appropriate terminology related to stoichiometry
 E2.2 calculate the molar mass of simple compounds with the aid of the
periodic table
 E2.4 solve problems involving relationships between the following
variables in a chemical reaction: quantity in moles, number of particles,
atomic mass, concentration of solution, and volume of solution
 E2.5 solve problems involving stoichiometric relationships in balanced
chemical equations
 E2.6 conduct an inquiry to determine the actual yield, theoretical yield, and
percentage yield
of the products of a chemical reaction and suggest
sources of experimental error
E3. demonstrate an understanding of the mole concept and its quantitative
relationships in chemical reactions. 


E3.1 describe the relationships between Avogadro’s number, the mole
concept, and the molar mass of any given substance
E3.2 describe some possible sources of experimental error in an
investigation of a chemical reaction, and explain how the errors would
affect the percentage yield of products of the reaction
E3.3 explain the relationships between the mole concept, the values of
coefficients, the number of particles, and the mass of substances in
balanced chemical equations