CHEM 101-069 Lab
Stoichiometry and Limiting Reagents Lab Report
Purpose: We are using the reaction of sodium hydroxide and calcium chloride to illustrate stoichiometry by demonstrating proportions needed to cause a reaction to take place.
Background: Just like a recipe would call for a specific amount of one ingredient to a specific amount of another, stoichiometry is the same exact method for calculating moles in a chemical reaction. Sometimes, we may not have enough of or too much of one ingredient , which would be defined as limiting and excess reagent, respectively. Ideally, every mole of each reagent would be used up, and theoretical yield, we are assuming that every last mole of the reactants would end up in the product. In other words, if 1 mole of CaCl2 was used, the product is expected to have 1mole of CaCl2, since Law of Conservation of Mass explains the conservation of all the molecules. However, any sample or experiment can carry room for error, and the actual product produced may be slightly less than what was originally present in the chemical equation, which is described by percentage yield, calculated by the following:
% yield = (actual/theoretical yield) x 100%
We used four test tubes, kept NaOH at a constant 4.00 mL in each tube, but adjusted the concentration of CaCl2. Tube 1 had 2.00mL, tube 2 had 3.50 mL, tube 3 had 5.00 mL, and tube 4 had 7.00mL of 1.00M CaCl2. We allowed them to react and filtered out the already