Stoichiometry And Limiting Reagents Lab Report

Stoichiometry and Limiting Reagents
Theodore A. Bieniosek

I. Purpose and Theory

The purpose of the experiment is to study and apply the processes of stoichiometric calculation on a controlled chemical reaction. We will be adding variable amounts of reactants in a chemical reaction in order to demonstrate the effect of limiting reagents. Based on the volumes of the reactants, and their respective molarities, we can calculate the theoretical yield of the reaction and compare it to the amount of products experimentally yielded. From the molarities of the solutions, the amount of moles can be calculated, and in turn fed into the balanced chemical equation to determine the theoretical yield.

II. Data and Calculations

Data
with Calcium Chloride: negative negative positive

Initial Mass of Filter Paper: .89 g .87 g .76 g
Final Mass of Filter Paper with precipitate: 1.14 g 1.27 g 1.15 g
Mass of Precipitate .25 g .40 g .39 g
[ (2 mole NaOH) / (1 mole CaCl2) ]*[ .005 mol CaCl2 ] = .010 moles NaOH needed to completely react CaCl2, only .005 moles available, therefore NaOH limits the reaction

Theoretical Yield of Ca(OH)2:
[ .005 moles NaOH ] * [ (1 mole Ca(OH)2 ) / (2 moles NaOH) ] = .0025 moles Ca(OH)2 formed
[ .0025 moles Ca(OH)2 ] * [ (74.0926 g Ca(OH)2 ) / ( 1 mole Ca(OH)2 ) ] = .1852 grams Ca(OH)2

Percent Yield
[ .25 g / .1852 g ] * 100 % = 134.989 %

Test #2

Volume CaCl2: 5.0 mL = .005 L
Volume NaOH: 4.0 mL = .004 L

Moles CaCl2 = (.005 L) * (1.0 mol/L) = .005 moles
Moles NaOH = (.004 L) * (2.5 mol/L) = .010 moles

Limiting Reactant:
NaOH, because precipitate was formed when Sodium Hydroxide