1 Minh-Huy Tran, Period 2&3 Piedmont Hills High School AP Chemistry Laboratory Experiment 2 –Stoichiometry and Hydrates September 18, 2018 Purpose: 1. Determine the mass of the reactants (aluminum and anhydrous copper (II) chloride/copper (II) chloride dihydrate) needed to create 2.00g of copper metal. 2. Extract the maximum amount of the copper metal possible from 5.0 g copper (II) sulfate pentahydrate. Introduction: This laboratory experiment focuses on stoichiometry. It is the study of mass in matter and is used to measure the quantitative relationships of the products and reactants in a chemical reaction. Stoichiometry involves the molar mass, the mass of a given substance, which is converted into moles in order to then be converted again into an unknown, such as the mass of a substance. The measurements in stoichiometry, grams, moles, liters, atoms, and molecules varies, but this lab only requires the units of mass, grams, and moles. The diagram below shows the order of how stoichiometry is calculated. The laboratory experiment also focuses hydrates. Hydrates, compounds that are usually crystalline, are comprised of water molecules chemically bonded another compound or an element. When a hydrate is dissolved in water, the water molecules that make up the hydrate separate from the other compound. The hydrates used in this experiment are copper (II) sulfate pentahydrate and copper (II) chloride dihydrate. Filtration, is an important process that is also needed for this laboratory experiment. It is the process in which a solid is separated from a liquid by adding a medium that only the liquid
2 Minh-Huy Tran, Period 2&3 can pass through. The use of a filter paper is crucial here, as it acts as the medium during filtration. The filter paper is folded in a specific way and is placed in a funnel which is contained in a flask. The steps to correctly fold the filter paper: 1. First fold the filter paper in half. 2. Fold the filter paper in half again 3. Open one of the flaps in the middle to make a cone. The steps to correctly filter a solution: 1. First fold the filter paper, and make into cone 2. Place a funnel in a flask 3. Put the filter paper in the funnel 4. Pour the solution into the filter paper 5. Let the liquid transfer into the flask and wait for the filtrate to dry
3 Minh-Huy Tran, Period 2&3 Most importantly, the laboratory experiment is a single replacement reaction that will be used for the stoichiometric calculations. A single replacement reaction is a reaction in which one one element replaces another element in a compound. This certain type of reaction relies on the reactivity series chart, which determines whether a single replacement reaction will occur or not based on the reactivity of different elements. An element with a higher reactivity will always replace the element with a lower reactivity. For this laboratory experiment, single replacement reactions will occur between aluminum metal and anhydrous copper (II) chloride, aluminum
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- Stoichiometry, Chemical reaction