THEORETICAL YIELD vs EXPERIMENTAL YIELD IN A COMBUSTION REACTION Suzanne Abou Shalah (Year 10) Science Faculty, The Illawarra Grammar School, Western Avenue, Mangerton, 2500 Abstract Stoichiometry in Chemistry is the study of quantitative relationships between the amounts of reactants used and the amounts of products formed. It is based on the Law of Conservation of Mass, which states that matter cannot be created or destroyed. In chemical reactions, the amount of matter present at the end of a reaction must be the same as the amount present at the beginning. The calculations depend on balanced chemical equations, which indicate the molar ratio of the reactants and products. In this study, stoichiometry was used to determine the amount of product produced of MgO in a combustion reaction. This was tested in an exothermic, combustion reaction of magnesium. The experiment was repeated multiple times, and the results found that although the experimental yield was similar to the theoretical yield, the mass of the products varied due to experimental errors.
Introduction This study aimed to investigate how experimental yield compares to theoretical yield in a combustion reaction of magnesium. The theoretical yield was calculated using stoichiometry and was used to calculate the percentage error when the experimental yield was found. Based on stoichiometry and the Law of Conservation of Mass, it was predicted that the amount of matter in the reactants will be the same as the amount of matter in the products.
moisture was released. Subsequently, the magnesium was placed in the crucible and heated over the bunsen burner with the lid remaining closed. Oxygen was periodically allowed in the crucible to aid combustion and to react. Combustion was complete when the Magnesium no longer ignited when exposed to oxygen; the product was white and flaky. Thereafter, the crucible with the lid was weighed once again and the mass was recorded. The following steps were repeated another 2 times and the results were recorded.
Method The following equipment was used in the experiment: crucible with lid, tongs, gauze mat, bunsen burner, magnesium. Firstly, the experiment was set up as shown in Figure 1 and the mass of the empty crucible was measured. Secondly, the piece of magnesium was coiled tightly and also measured along with the crucible and lid. To ensure consistent mass throughout the trials, the crucible was heated over the bunsen burner, until the mass was stable, and all 35
