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Lab Report Stoichiometry

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Stoichiometry is the process of organizing the relative amounts of products and reactants in a chemical equation. The ratios in a chemical equation can be used alone to determine the number of moles or in conjunction with atomic mass to determine the number of grams of a reactant or product if given the amount in either moles or grams of another reactant or product. The purpose of this experiment is to use stoichiometric ratios of a balanced equation to determine the limiting reagent based on the quantity of product.
A limiting reagent is the reactant that is used up the quickest in the chemical reaction. It limits the amount of product the reaction can produce. Excess reagent is any reactant that is not used up completely during a chemical …show more content…

The experimental testing simply divides the aqueous product into two parts, and tests one with each reactant. Whichever one causes a reaction is the limiting reactant, and the other is in excess. Calculations can also be done to predict which is the limiting reactant. Compare (experimental mols 〖CaCl〗_2)/(experimental mols NaOH) to the stoichiometric ratio of (1 mol 〖CaCl〗_2)/(2 mols NaOH), if the former is less than the latter, CaCl2 is limiting. If they are equal, neither is limiting and the reaction is purely stoichiometric. If the experimental ratio is greater than the theoretical, then NaOH is limiting. In this experiment, CaCl2 should be limiting for the first few trials, then NaOH should become limiting as the amount of CaCl2 used is …show more content…

However, the chemical testing showed that it was actually only limiting for the first two. From this graph, there is no plateau evident. However, the theoretical calculations suggest the plateau should occur between the last two data points. The plateau would show where the theoretical yield switches from dependent on CaCl2 to dependent on NaOH.

Conclusion:

The purpose of this experiment was to use stoichiometric ratios of the balanced equation between NaOH and CaCl2 to determine the limiting reagent based on the quantity of products. It was determined through chemical testing that the first two amounts of CaCl¬2 were limiting the reaction and the second two amounts had NaOH as a limiting reagent. This is despite the calculations indicating that the third amount of CaCl¬2 should also limit the reaction. Overall, trials 1, 2, and 4 proved the theoretical results while the third trial disproved them. However, the results were not perfect, so this is likely what caused the abnormal result in the third trial. Trial two was very good with a 99.25% yield. Trial one’s results are a little concerning, as it produced 27.84% more than expected. The error that could have resulted in these differences includes improper measurement of CaCl2, such as reading from the top of the meniscus instead

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