CaCl2⚫2H2O + Na2CO3⚫H2O 2NaCl + CaCO3⚫3H2O
mass 3.68g 5.05g
volume 0.0500L 0.0500L
molarity 0.500M 0.814M
initial moles 0.0250mol 0.0407mol 0 0
change in moles -(0.0250mol) -(0.0250mol) +2(0.0250mol) +(0.0250mol)
final moles 0 0.0157mol 0.0500mol 0.0250mol
0.0250mol CaCO3 x 100.09g CaCO3 = 2.50g CaCO3
1 mol CaCO3
Experimental CaCO3 Precipitate: 2.87g CaCO3
Total % Uncertainty = 7.91%
DISCUSSION:
In this lab, calcium carbonate dihydrate, CaCl2⚫2H2O was reacted with sodium carbonate monohydrate, Na2CO3⚫H2O to yield a precipitate of calcium carbonate, CaCO3. To make a 50.0mL solution of 0.5M CaCl2⚫2H2O, the appropriate number of grams was measured. It was also made sure that there was enough Na2CO3⚫H2O to fully react with the CaCl2⚫2H2O. The theoretical yield of CaCO3 precipitate was 2.50g. Our experimental yield was 2.87g, resulting in a percent yield of 115%. A high percent yield may have bee the result of many different errors. The percent error was 14.8% and the percent uncertainty was 7.91%. Therefore systematic errors were mainly sources of error in our experiment.
Errors in this experiment may have been due to the fact that not all of the water had evaporated from the CaCO3 precipitate giving it a greater mass. Also, a paper filter by itself was used to drain out the water from the precipitate as opposed to a buchner funnel, so that not all of the water was drained out. Another error may have been incorrect weighing of the CaCl2⚫2H2O so that some extra reacted with the excess Na2CO3⚫H2O resulting in a greater yield of precipitate. As well, when weighing the CaCO3 precipitate, there may have been extra weight added to the precipitate due to touching the filter paper with our hands.
To improve this experiment, we would make sure to give the precipitate more time to dry. As well, we would use a buchner funnel to drain as much water out as possible. When weighing substances, we would be careful in measuring more accurately. Also when touching the CaCO3 precipitate we would wear gloves so that no extra weight is added from our fingers.
CONCLUSION: In this experiment, a yield of 2.87g of CaCO3 was produced.
