Stoichiometry Of Chemical Reactions Sample

Introduction

This experiment aims to apply stoichiometric principles to determine the theoretical yield, limiting reactant, and percent yield of a precipitation reaction. Since 1792, when Jeremias Benjamin Richter introduced the concept of stoichiometry, these calculations have formed the foundation of quantitative chemistry. The reaction between 50 mL of 0.1 M barium chloride and 50 mL of 0.2 M sodium sulfate yields barium sulfate as a precipitate. The Law of Conservation of Mass dictates that mass is neither created nor destroyed, allowing the calculation of theoretical yield using balanced equations (Brown et al., 2015). To determine the limiting reactant, the molar quantity of each reactant must be compared against the 1:1 stoichiometric ratio. While the molar volume of an ideal gas at standard temperature and pressure remains 22.4 L/mol, this experiment focuses exclusively on aqueous solutions. The principles of stoichiometry rely heavily on Dalton's atomic theory, formalized in 1803.

Materials and Methods

The laboratory procedure required precise measurements of aqueous solutions. Approximately 50.0 mL of 0.100 M barium chloride was measured using a volumetric flask and combined with 50.0 mL of 0.200 M sodium sulfate in a 250 mL beaker. The resulting barium sulfate precipitate was isolated using vacuum filtration through Whatman No. 40 filter paper, dried in an oven at 105°C for 30 minutes, and weighed using an analytical balance (±0.0001 g). The calculation of theoretical yield, based on the balanced chemical equation, preceded the experimental execution to anticipate the precipitate mass.

Results

The determination of the limiting reactant indicated that barium chloride limited the reaction; it was provided in fewer moles (0.0050 mol) than required by the 1:1 stoichiometric ratio with sodium sulfate (0.0100 mol). The experimental yield of barium sulfate was determined to be 1.0532 g.

Discussion

The theoretical yield, calculated from the 0.0050 moles of the limiting reactant (barium chloride), was 1.1668 g of barium sulfate. Consequently, the calculation of percent yield from the experimental data resulted in a 90.26% yield. Standard laboratory yield calculations typically exceed 90% under ideal conditions. The 9.74% deviation from the theoretical maximum likely stems from mechanical losses during filtration, such as precipitate adhering to the beaker walls, or incomplete precipitation due to slight solubility of barium sulfate in water at room temperature. These quantitative results confirm the Law of Definite Proportions originally formalized by Antoine Lavoisier (Zumdahl & Zumdahl, 2020).

References

Brown, T. L., LeMay, H. E., Bursten, B. E., & Murphy, C. J. (2015). Chemistry: The Central Science. Pearson.

Zumdahl, S. S., & Zumdahl, S. A. (2020). Chemistry. Cengage Learning.