October 14, 2014
Abstract: The purpose of the lab, Stoichiometry of a Precipitation Reaction, is to be able to calculate the amount of a second reactant we need to react with the reactant one. You must calculate the amount of the second reactant using stoichiometry to figure out what amount is needed. After the amount is calculated, you then can add it to the first reactant and it will give you a full reaction. To figure out what you need you have to use stoichiometry. My calculation for the second reactant was: 1.0g CaCl2*2H2O(1mol CaCl2*2H2O/147g CaCl2*2H2O)(1mol Na2CO3/1mol CaCl2*2H2O)(106g Na2CO3/1mol Na2CO3) = 0.72g Na2CO3. The final, when its dried in the paper filtered weighed at 1.6 grams.
Experiment and Observations: As I performed the lab, I had to retrieve all my equipment’s from my labpaq. As I started to setup, I had to weigh out 1.0 gram of CaCl2*2H2O on the digital scale. After it was weighed, it was added to the 100 mL beaker and 25 mL of distilled was added and stirred. Next, I had to figure out the amount of the second reactant, so that it can be added to the solution. I had to perform stoichiometry to figure out the amount of Na2CO3 is needed to make a precipitate of calcium carbonate. After the calculations, I arrived at .72 grams of Na2CO3 and rounded to the nearest tenth to mix with 25 mL of distilled water. After both of the reactants were mixed separately with distilled water, they both were clear color. As soon as you added the solution of Na2CO3 to CaCl2*2H2O the color of solution changed to a cloud white color. When both solutions are mixed, the paper filter that was provided with the lab must be weighed and recorded. Then you pour the solution into the paper filter to filter out the precipitate and dry the filter to weigh the mass of the precipitate when it dries. After it dried, it was weighed and stoichiometry was performed to see what the