Calculating the Percent Yield of Copper Lab Report PDF

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Lab report submitted in University/Academic Grade 11 Chemistry. This was for the lab where we had to calculate the percent yield of copper. ...

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Analysis of the Results from the Percent Yield of Copper (II) Hydroxide Lab, Involving the Double Displacement Reaction Between Sodium Hydroxide and Copper (II) Sulphate

SCH3UI Wednesday, May 9th, 2018

2 Percent Yield Description and its Importance in the Manufacturing Sector: The percent yield in a reaction is the percent ratio of the actual yield to the theoretical yield of a substance, multiplied by 100. As a percentage, it says how much of the theoretical product yield is actually created, during an experiment. The percent yield is important in manufacturing sectors because it allows companies to know what reactions and processes are the most efficient and economical for them. Having a low percent yield can mean that reactants are being wasted, which is not efficient nor economical for companies. For this reason, understanding the percent yields is very important for companies to know. Potential Safety Concerns Associated with the Reactants and Products from the Experiment: For the reactants, sodium hydroxide can cause skin corrosion (severe burns), serious eye damage, respiratory tract irritation, and has an acute aquatic toxicity. Sodium hydroxide is particularly harmful to humans if it is absorbed through the skin or if it is swallowed. Copper (II) sulphate can be moderately toxic by ingestion and inhalation, a body tissue irritant, an irritant to eyes and skin, and can cause damage to target organs such as the liver, kidneys, lungs, and spleen. For the products produced, sodium sulphate can be an eye and skin irritant, and it is hazardous to ingest or inhale. Copper (II) hydroxide can be a hazardous eye and skin irritant, and is also hazardous to ingest or inhale. Materials Used During the Experiment: • 2 Beakers • 2 Erlenmeyer Flasks • 2 Funnels • 2 Filter Papers • 1 Scale • 2 Scoopulas • 0.96g of Solid NaOH • 1.40g of Solid CuSO4 • Distilled Water in a Bottle Results of the Experiment: Table 1: Qualitative and Quantitative Observations for the Reactants and Products in the Experiment Chemical NaOH(s)

Qualitative Observations • Rough • White • Solid • Opaque

Quantitative Observations • 0.96 grams

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NaOH(aq)

CuSO4(s)

CuSO4(aq)

Cu(OH)2(s)

Na2SO4(aq)

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Odorless

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Transparent Colorless Odorless Low Viscosity Aqueous Fine Crystals Light Blue Solid Opaque Odorless Odorless Blue Transparent Low Viscosity Aqueous Dark Turquoise Rough Odorless Dull Opaque Solid Aqueous Transparent Colorless Odorless Low Viscosity

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1.40 grams

Actual Yield: 1.76 grams • Theoretical Yield: 0.856g • Percent Yield: 206%

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Discussion Questions: (Calculations on Lined Paper) 1. 2NaOH(aq) + CuSO4(aq) → Cu(OH)2(s) + Na2SO4(aq) 2. Double displacement reaction that produces a precipitate. 3. The reactants were aqueous sodium hydroxide and aqueous copper (II) sulphate which react, producing solid copper (II) hydroxide and aqueous sodium sulphate. 4. Therefore, the limiting reactant is copper (II) sulphate. 5. Therefore, the theoretical yield is of copper (II) hydroxide is 0.856g. 6. Therefore, 0.26g of excess sodium hydroxide exists in aqueous form. 7. Therefore, the percent yield is 206%.

4 8. a) The percent yield could be lower than 100% if some of the product is left on the container (flasks/beakers), some of the products are lost while transferring liquids, side reactions occur or if unclean utensils (contaminations, impurities) were used. b) The percent yield could be higher than 100% if problems with evaporation occur or if unclean utensils (contaminations, impurities) are used. The actual yield of copper (II) hydroxide was 1.79g, this data having being gathered during the experiment. The actual yield of copper (II) hydroxide was calculated by weighing the filter paper on its own, using a scale, weighing the filter paper with the product on it, and then subtracting the mass of the filter paper alone from the filter paper with the product on it (3.88g - 2.12g = 1.76g). The theoretical yield of copper (II) hydroxide was 0.856g, as shown in table 1. The theoretical yield of copper (II) hydroxide was found by first discovering which reactant was the limiting reactant. To find the limiting reactant, the moles of each reactant were obtained by converting their masses into moles. The moles of each reactant was then was put into a Stoichiometric ratio (1 mol of Cu(OH)2 being the numerator and the amount of moles of the reactant being the denominator). Copper (II) sulphate was discovered to be the limiting reactant because it produced the least amount of copper (II) hydroxide (0.00877 mol). The amount of copper (II) hydroxide created by the limiting reactant (copper (II) sulphate, 0.00877 mol) was then converted into mass, which was the theoretical yield (0.856g). The percent yield was 206%, which is clearly well over 100%. As mentioned in 8b of the discussion questions, this could have been due to impurities and contaminations caused by unclean utensils used during the experiment or the liquid had not been fully evaporated from the copper (II) hydroxide, thus, making its percent yield much greater than it should have been.

5 References GCSE Bitesize: Atom economy. (n.d.). Retrieved from http://www.bbc.co.uk/schools/gcsebitesize/science/add_ocr_gateway/chemical_economics/atom economyrev2.shtml Helmenstine, A. M. (2018, January 21.). What Is Percent Yield? Review Your Chemistry Concepts. Retrieved from https://www.thoughtco.com/definition-of-percent-yield-605899...