SCH 3U
Limiting Reagent and Percent Yield Lab
Introduction:
In this lab, you will be performing a double displacement reaction and measuring the mass
of the product produced. Calcium chloride reacts with sodium carbonate to form calcium
carbonate. Calcium carbonate is a precipitate. This means that it is a solid and it can be
separated from the rest of the products using filtration. The calcium carbonate will be dried
overnight and then weighed. We will see how close the mass of calcium carbonate
recovered is to the mass we calculated using stoichiometry.
Chemical reaction:
calcium chloride (aq) + sodium carbonate (aq)  calcium carbonate (s) + sodium chloride (aq)
Materials:
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filter paper
funnel
stirring rod
graduated cylinder
2 beakers
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electronic balance
sodium carbonate
calcium chloride
water
Procedure:
1. Put 0.75 g of calcium chloride in a small beaker. Add 25 ml of water and stir until the
calcium chloride has dissolved. If necessary, you may add a little more water so it is
completely dissolved.
2. Put 0.75 g of sodium carbonate in a second beaker. Add 25 ml of water and stir until it
has completely dissolved. If necessary, you may add a little more water so it is completely
dissolved.
3. Combine the calcium chloride solution and the sodium carbonate solution. The white
precipitate that forms is the product, calcium carbonate.
4. Find the mass of a clean piece of filter paper. Write the mass of the filter paper and your
names on the filter paper in pencil. Fold the filter paper into quarters and put it into the
funnel.
5. Filter the mixture through the filter paper. The filter will stop the calcium carbonate. The
extra water, sodium chloride solution, and the excess reagent will pass through the filter.
Rinse your beaker out with some clean water to make sure all of the calcium carbonate is
washed into the filter. The liquid that passes through the filter can be disposed of down the
drain.
6. Bring your filter paper to the front of the class, where it will be dried out overnight.
Observations:
mass of calcium chloride
mass of sodium carbonate
mass of filter paper alone
mass of filter paper and precipitate (after drying)
Questions and Calculations:
1. Write a balanced chemical equation for the reaction used in this lab.
2. In the chemical equation, what do the symbols “(aq)” and “(s)” mean? How do these
symbols help you determine which chemicals can be filtered out?
3. Calculate the following values:
a) moles of calcium chloride used
b) moles of sodium carbonate used
4. Identify the limiting and excess reagents.
5. Using stoichiometry, calculate the theoretical mass of calcium carbonate.
6. In steps 1 and 2 of the procedure, it says to add more water, if necessary, to help dissolve
the ionic compounds. Will adding water affect the results? Explain why or why not.
7. Calculate the percent yield of calcium carbonate.
8. If you did not wash all of the calcium carbonate out of the beaker and into the filter
during step 5, would your percent yield be larger or smaller? Explain.
9. If you did not allow the calcium carbonate and filter to dry out completely overnight,
would you expect the percent yield to be larger or smaller? Explain.