LAB - STOICHIOMETRY; FORMATION OF A PRECIPITATE(AP)
NAME______________________
Purpose: to predict the amount of precipitate formed in a chemical reaction
Equipment: 2 250 mL beakers, glass funnel, coarse filter paper, stir rod, filter stand, balance, drying oven
Materials: anhydrous sodium carbonate ( Na 2 CO3 ) , calcium chloride ( CaCl2  2H 2 O ), distilled water
Procedure:
1) Rinse the two beakers with distilled water. Make sure the two beakers are also dry.
2) Measure out about 2 g of sodium carbonate and place it in one beaker. Record the actual mass used.
3) Measure out about 2 g of calcium chloride and place it in the other beaker. Record the actual mass used.
Predictions
** Make sure to complete Conclusion #1 before this step **
a) What is the limiting reactant? What is the excess reactant?
_________ g Na 2 CO3
_________ g CaCl2  2H 2 O
b) How many grams of precipitate do you anticipate?
4) Add enough distilled water to each beaker to dissolve the solids. Begin with about 50 mL of water, and add
more if necessary.
5) SLOWLY mix the two solutions together. What do you see occurring?
6) Using as little distilled water as possible, rinse out the empty beaker. Pour the rinse in the full beaker.
7) Set up your filtering apparatus as shown by your instructor. Rinse the empty beaker thoroughly, dumping the
rinse into the sink. Place the empty beaker under the funnel in the filter apparatus. Record the mass of the
filter paper. Write your initials in pencil along the edge of the filter paper.
8) With constant swirling, pour the slurry into the filter SLOWLY. Make sure the filter does not overflow.
Note the color of the filtrate (liquid coming through the funnel). What do you observe?
9) Once the beaker is empty, use as little water as possible to rinse out the beaker. Pour the rinse through
the filter, trying to get as much precipitate as possible into the filter apparatus. If there is enough time
gently pour some clean distilled water through the filter to wash the precipitate.
10) Gently remove the full filter paper from the funnel and shake off any excess water drops.
11) Place the filter in the drying area to sit overnight.
12) Once the filter is dry, record the mass of the filter paper with the precipitate.
LAB - STOICHIOMETRY; FORMATION OF A PRECIPITATE(AP)
NAME______________________
Data:
a) mass of filter paper
__________ g
b) mass of filter paper + precipitate after drying
__________ g
Calculations:
______________ 1) Calculate the amount of precipitate you got. (b - a)
2) Calculate the percent yield of your precipitate.
Percent Yield 
#1
(Procedure #3b)
Conclusions:
1) Write the correct balanced equation with phase notation for the reaction you performed.
What is the formula of the precipitate?
2) List any error sources which could account for any error (% yield less than 100).
3) If you began with 3.50 g of sodium carbonate and 3.00g of calcium chloride dihydrate:
a) What is the limiting reactant? What is the excess reactant?
b) How many grams of precipitate do you expect?
x100%