Unit 4 Lab Stoichiometry In Chemistry 1806 Purpose To Practi

Unit 4 Lab Stoichiometrychem 1806purpose To Practice The Concept Of

Perform a laboratory experiment focused on stoichiometry involving the reaction of calcium chloride (CaCl₂) with sodium carbonate (Na₂CO₃), producing calcium carbonate (CaCO₃) precipitate. The procedure includes weighing reactants, preparing solutions, conducting the reaction, filtering and drying the precipitate, and calculating theoretical and actual yields, along with percent yield. Students will also perform calculations to determine the amount of sodium carbonate needed for the reaction, write the balanced chemical equation, and analyze experimental vs. theoretical outcomes.

Paper For Above instruction

In this experiment, the primary objective is to understand stoichiometry through the reaction of calcium chloride and sodium carbonate to produce calcium carbonate precipitate. The procedure involves multiple steps including weighing, solution preparation, reaction, filtration, drying, and calculation of yields, which collectively reinforce concepts of molar ratios and quantitative analysis in chemistry.

Initially, students are instructed to weigh 1.0 g of calcium chloride (CaCl₂) using a digital scale and record this mass. This gathered data forms the basis for subsequent molar calculations. The calcium chloride is then dissolved in 25 mL of distilled water in a beaker, creating a stock solution. Simultaneously, students will calculate the amount of sodium carbonate (Na₂CO₃) required to react completely with the known amount of calcium chloride, based on the balanced chemical equation:

CaCl₂ (aq) + Na₂CO₃ (aq) → CaCO₃ (s) + 2 NaCl (aq)

This balanced equation indicates a molar ratio of 1:1 between calcium chloride and sodium carbonate, which simplifies the calculation of the necessary sodium carbonate mass based on the initial calcium chloride mass.

Following the calculation, students weigh out the calculated amount of sodium carbonate and dissolve it in another 25 mL of distilled water to prepare a sodium carbonate solution. This solution is then poured into the calcium chloride solution, initiating the precipitation of calcium carbonate. Observations of the reaction, such as the formation of a solid and any bubbling or color change, are documented as qualitative data.

The precipitate is then isolated by filtering the mixture through a pre-weighed filter paper. To ensure complete transfer, the beaker is rinsed with small volumes of distilled water, and the filtrate is discarded or retained for further analysis if necessary. The filter paper with the precipitate is dried, either overnight or for several days, then weighed to determine the mass of the precipitate + filter paper. The actual yield of calcium carbonate is calculated by subtracting the mass of the filter paper from the combined weight.

Students then compute the theoretical yield of calcium carbonate based on the initial amount of calcium chloride, utilizing molar mass and molar ratio calculations. The percent yield is obtained by dividing the actual yield by the theoretical yield and multiplying by 100%. This analysis allows students to understand efficiency and sources of experimental error in chemical reactions.

Finally, the report should include the balanced chemical equation, calculations for sodium carbonate needed, and detailed discussion of the results, including potential reasons for discrepancies between theoretical and actual yields. Visual documentation, such as photographs of the precipitate and filter paper, can provide additional context and aid comprehension.

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