In chemical reactions, the significance of knowing the limiting reactant is high. In order to increase the percent yield of product, increasing the limiting reactant, possibly, is the most effective. In this experiment we were able to calculate limiting reactants from the reaction of CaCl2. 2H2O + K2C2O4.H2O(aq). As a group, we obtained our salt mixture of calcium chloride and potassium oxalate, and weighed the mixture. We were able to make an aqueous solution from the mixture and distilled water. We boiled and filtered off the solution, leaving the precipitate. Once the precipitate was dried overnight, it was weighed and the mass was measured. Then we calculated the moles of the precipitate.
From these calculations, we established moles of the limiting reactant, were the same amount of moles in the product based on the stoichiometrically balanced equation. Next the percent yield of the limiting reactant was calculated.
In Part B of this experiment, two solutions were added to the aqueous product in order to determine the limiting reactant. Once each solution was added, we were able to visibly see the precipitate forming when 0.5 M CaCl2 was added. This made us conclude the limiting reactant was in fact CaCl2.
Stoichiometry is a section of chemistry that involves using relationships between reactants and/or products in a chemical reaction to determine desired quantitative data. Doing stoichiometry can calculate masses, moles, and percent’s with a chemical equation. The use of stoichiometry is how we were able to find the limiting reagent in this lab. We know that the limiting reagent is the chemical that will be used up first.
Two factors affect the yield of product in a chemical reaction: the amounts of starting materials and the percent yield of the reaction. Under certain conditions such as temperature and pressure, can be adjusted to increase the yield of a desired product in a chemical reaction
References: Tro, Nivaldo. Chemistry A Molecular Approach. 3rd ed. Boston, MA: Pearson Education, Inc.; Beran, J. A. Laboratory Manual for Principles of General Chemistry. 8th ed. Hoboken, NJ: John Wiley & Sons, Inc.; 2009 Beran, J. A. Laboratory Manual for Principles of General Chemistry. 9th ed. Hoboken, NJ: John Wiley; 2010 UC Davis ChemWiki. Stoichiometry and Balancing Reactions. http://chemwiki.ucdavis.edu/Analytical_Chemistry/Chemical_Reactions/Stoichiometry_and_Balancing_Reactions UCCS Chem 103 Laboratory Manual. Experiment 3 Limiting Reactants. http://www.uccs.edu/Documents/chemistry/nsf/103%20Expt3V-LR.pdf Masterson, W, Hurley, C. Chemistry: Principles and Reactions. 6th ed. Belmont, CA: Brooks/Cole Cengage Learning; 2009.