Department of Chemistry
Stoichiometry of a Precipitation Reaction
Submitted by Hendy Zelishovsky
Date Submitted: 4/26/2012
Date Performed: 4/25/2012
Lab Section: Chem-180-DL1
Course Instructor: Dr. Cynthia Spencer
The purpose of this experiment is to use stoichiometry to predict how much of a product will be made in a precipitation reaction, to measure the reactants and products of the reaction correctly, to figure out the actual yield vs. the theoretical yield and to calculate the percent yield.
First, 1.0 g of CaCl2·2H2O was put into a 100-mL beaker and 25 mL of distilled water was added. The two ingredients were stirred to create a calcium chloride solution. Then, stoichiometry was used to determine how much Na2CO3 was needed for a full reaction: First, 1 g of CaCl22H2O was converted to moles: 0.00680 moles. The mole ratios of CaCl22H2O and Na2CO3 was seen to be 1:1. Then, moles of Na2CO3 were converted to grams: 0 .72 g. The measure of CaCo3 was predicted to be 0.00680 moles. 0.00680 moles converted to grams is 0.68 grams.
Then, 0 .72 grams of Na2CO3 was measured into a paper cup because that was the measure calculated for Na2CO3 using stoichiometry in the step before. 25 mL of distilled water was added and stirred. Then, that solution was poured into the 100 mL beaker and it formed a precipitate (calcium carbonate) instantly with the calcium chloride solution.
Next, a filteration system was set up: A small cup was placed inside a larger cup for support and a funnel placed in to the small cup. Then, a 1.1 gram circle of filter paper was folded in half twice and one section of the folds in the filter paper was opened to fit into the funnel. Then, the solution...