CHM11L - EXPERIMENT NO. 5 - STOICHIOMETRY

EXPERIMENT NO. 5

STOICHIOMETRY

OBJECTIVES

1. To differentiate limiting reactant  and excess reactant

2. To compute the theoretical yield and the percent yield  of a chemical reaction.

CONCLUSION

Stoichiometry is the quantitative study of reactants and products in a chemical reactions. In this experiment, we can conclude that Limiting reactant is the reactant in a chemical reaction that limits the amount of product that can be formed. Therefore, whenever all of the limiting reactant is consumed, the reaction will stop. The chemical reaction that remains when a reaction stops and the limiting reactant is completely consumed is called Excess Reactant. The Excess reactant remains because there is nothing with which it can react.

Theoretical Yield of a reaction is the amount of product that would be formed if the reaction went to completion. It is calculated from the balanced equation based on the amount of reactants used. First, you must balance the reaction and determine the stoichiometry or ratios of reactants to products. Then assume that each reactant is a limiting reactant and compute the amount of product. Next, determine which reactant is limiting, this has a smaller amount of product. Lastly, calculate the grams of product corresponding to the number of moles expected by converting the moles to grams.

To compute the percent yield, divide the actual yield, amount based on the experiment,  by the theoretical yield, computed product, and multiply the product by 100%. Percent yield is the efficiency of a chemical reaction.