Stoichiometry of a Precipitation Reaction Key

Stoichiometry of a Precipitation Reaction Final Report Student Name Student ID Lesson Stoichiometry of a Precipitation Reaction Institution National University Session Course Instructor Test Your Knowledge 1. Match each term with the best description. The chemical compounds that are present before a reaction occurs The compounds produced from the reaction Unit of measure, containing Avogadro's number The quantitative proportion of reactants to products Two solutions are mixed and an insoluble substance forms 1 Reactants 2 Products 3 Mole 4 Stoichiometry 5 Precipitation reaction 6 Chemical equation 7 Hydrate An illustration of the reaction that occurs between two or more chemical compounds A solid compound that contains water molecules 2. Match each compound with its correct molar mass. H2SO4 1 98 g/mol Ca(OH)2 2 74 g/mol CuSO4 • 5H2O 3 250 g/mol K3PO4 4 212 g/mol 3. Match each hydrate formula with the correct chemical name. Magnesium sulfate dihydrate 1 MgSO4·2H2 O Magnesium sulfate monohydrate 2 MgSO4·H2 O Magnesium sulfate heptahydrate 3 MgSO4·7H2 O Magnesium sulfate hexahydrate 4 MgSO4·6H2 O Magnesium sulfate trihydrate 5 MgSO4·3H2 O Magnesium sulfate pentahydrate 6 MgSO4·5H2 O Exploration 1. A chemical equation is a written representation of the process that occurs in a chemical reaction. True False 2. The term for a reaction where two solutions are mixed and an insoluble substance forms is called a _____ reaction. chemical soluble precipitation stoichiometry balanced 3. A mole is a unit of measure, describing the amount of a chemical substance that contains as many atoms, ions, or molecules as there are in exactly 12 grams of pure Nickel. True False 4. Stoichiometric quantities can be used to maximize the amount of product produced from a chemical reaction. True False 5. A _____ is a solid compound that contains _____ molecules. hydrate; water water molecule; hydrated hydrate; solid hydrate; hydrated Exercise 1 1. Given that a theoretical yield for isolating Calcium Carbonate in this experiment would be 100%. From that information and based on the results you obtained in this experiment, describe your success in the recovery of calcium carbonate and suggest two possible sources of error that would have caused you to not obtain 100% yield. I personally think one of the reasons why I was not able to get close to 100% was because the scale does not give you the hundredths place and therefore if my weight was 1.59 but it only showed me at 1.5 I am theoretically losing almost .10g each time I weight something. Another possibility could be that the materials failed to react or their product was not efficiently captured. Also due to my inexperince in a lab I think it could be the latter of the two. I only got about ~86% but it could be worse. 2. What impact would adding twice as much Na2CO3 than required for stoichiometric quantities have on the quantity of product produced? There would most likely be a remaining amount of CaCO3 because there wouldn't be enough CaCl2 to react completely with the NaCO3. 3. Determine the quantity (g) of pure CaCl2 in 7.5 g of CaCl2 •9H2 O. Show your work. 40.08 + 2 x 35.45 = 110.98/gmol 40.08 + 2 x 35.45 + 9 x 18.02 = 273.16 g/mol 7.5 g CaCl2 9H2O by 110.98/273.16 = 3.047 grams CaCl2 4. Determine the quantity (g) of pure MgSO4 in 2.4 g of MgSO4 •7H2 O. Show your work. MgSO4*7H2O = 246.47 g/mol MgSO4 = 120.366 g/mol 5. Conservation of mass was discussed in the background. Describe how conservation of mass (actual, not theoretical) could be checked in the experiment performed. Conservation mass discussed in the background states that the total mass of the reactants should equal the same total mas of the products produced. We can check this by weighing the reactants and the products. Data Table 1: Stoichiometry Values Initial: CaCl 2•2H2O (g) 1.50 g Initial: CaCl 2•2H2O (mol) 147.02 g/mol Initial: CaCl 2 (mol) 0.0102 mol Initial: Na 2CO3 (mol) 106 g/mol Initial: Na 2CO3 (g) 1.0816 g Theoretical: CaCO3 (g) 1.02 g Mass of Filter paper (g) 1.2 g Mass of Filter Paper + CaCO3 (g) 2.6 g Actual: CaCO3 (g) 1.4 g % Yield: 86 Competency Review 1. The chemicals that are present before a reaction occurs are called _____, and the chemicals produced from the reaction are called _____. products; reactants reactants; products 2. A precipitation reaction produces insoluble substances that can be removed from the solution. True False 3. The quantitative proportion of reactants to products in a chemical reaction is known as _____. the Law of Conservation of Mass stoichiometry the precipitation coefficient 4. The molar mass of H2 O is approximately 18 grams; thus, one mole of H2 O weighs approximately 18 grams. True False 5. How many moles of water are in the compound copper sulfate pentahydrate? 3 5 6 7 6. In order to calculate the theoretical maximum amount of product produced in a precipitation reaction, you must _____. convert grams of reactants to moles determine how many moles of reactants are necessary to reach stoichiometric quantities determine moles of product from the reaction convert moles of product to grams All of the above 7. A reaction is performed in a lab whereby two solutions are mixed together. The products are a liquid and a solid precipitate. What procedures would facilitate measurement of actual yield of the solid? Calculate the maximum potential yield, and apply the final value in the appropriate equation. Use filter paper to isolate and dry the precipitate, and then determining mass of the solid. Find the cumulative mass of the precipitate and solid, and extrapolate the molecular mass. All of the above 8. Why might the actual yield of a precipitation reaction not equal the theoretical yield? Environmental conditions may cause variations in the water content of the hydrate. The reaction did not go to completion. The precipitate was not properly isolated. All of the above Extension Questions A student carries out the precipitation reaction shown below, starting with 0.030 moles of calcium nitrate. The final mass of the precipitate is 2.9 g. Answer the questions below to determine the percent yield. 3Ca(NO3 )2 (aq) + 2Na3 PO4 (aq) → Ca3 (PO4 )2 (s) + 6NaNO3 (aq) 1. a. Which product is the precipitate? b. How many moles of the precipitate would one expect to be produced from 0.030 moles of calcium nitrate? c. How many grams of solid do you expect to be produced? d. What is the percent yield? A. Ca3(PO4)2 B. 0.010 moles of Ca3(PO4)2 can be expected to be produced C. 3.1g of Ca3(PO4)2 D. Percent yield = 93.5%