Stoichiometry Toombs Practice Test

Unit 3 CHEMISTRY 11 STOICHIOMETRY Toombs PRACTICE TEST Use these questions as a guide as a START to your studying. Each question below represents a concept and type of question that you should feel confident completing. If you have difficulty with one of the questions below, then you should go back to your notes and worksheets to more fully review and practice this concept. Be sure to use the resources (TUTORIAL VIDEOS!) on the website to help you fully understand these concepts. Just completing these questions IS NOT ENOUGH to adequately prepare you for the test. REDOX EQUATIONS Balance the following REDOX equations: 1. a) Fe + Ag+ à Ag + Fe+2 b) ACTIVITY SERIES Complete the following single replacement reactions: 2. a) Cu + H2O à b) Cl2 + NaI à Al + Pb+2 à Pb + Al+3 ENERGY in CHEMICAL REACTIONS 3. Define and draw a diagram for an exothermic reaction and an endothermic reaction. In your answer, explain how stoichiometry affects the kJ of energy involved in a reaction. STOICHIOMETRY 4. If 4.11 g of Iron are added to 317 mL of Hydrogen Sulphide gas at STP, will both reactants be totally consumed? What mass of products will we obtain? 5. 35.0 g of copper (II) iodide reacts with 39.0 g of silver nitrate. a) calculate the grams of each product formed b) state the limiting reagent c) determine the amount, in grams, of the excess reagent d) show your check of the law of conservation of mass PERCENT AND THEORETICAL YIELD: 6. a) Calculate the theoretical yield of C2H5Cl if 112 g of C2H5OH is reacted with 34.7 g of PCl3, forming C2H5Cl and H3PO3. b) If 23.7 g of C2H5Cl is produced, what is the percent yield? 7. a) Uranium reacts with Bromine to form Uranium (VI) bromide in a synthesis reaction. If the reaction starts with 100. g of Uranium and the percent yield of this reaction is 83%, what is the actual yield of Uranium (VI) bromide? b) Knowing that the percent yield is 83%, how much Uranium should be reacted to produce 350 grams of Uranium (VI) bromide? YOU MUST CLEARLY SHOW YOUR PROCESS THROUGHOUT EACH CALCULATION QUESTION, IN ORDER TO FULLY COMMUNICATE YOUR UNDERSTANDING OF CONCEPTS. PERCENT COMPOSITION and EMPIRICAL AND MOLECULAR FORMULAS: 8. Determine the percent composition of calcium phosphate. Report your answers to 3 SF. 9. Glucose contains 40.0% Carbon, 6.70% Hydrogen, and 53.3% Oxygen by mass. a) What is the empirical formula of Glucose? b) What is the molecular formula of glucose, if the molar mass of Glucose is 180. g / mole? 10. When Uranium reacts with Bromine, the product is not always Uranium (VI) bromide. In a particular reaction, 100. grams of Uranium reacted fully to produce 201 g of product. Determine the chemical formula of the product formed. ANSWER KEY 1 a) Fe + 2Ag+ à 2Ag + Fe+2 b) 2Al + 3Pb+2 à 3Pb 2 a) Cu + H2O à no reaction !!! + 2Al+3 Copper is below H+ on the activity series chart and therefore will not replace the H+ in water (or in an acid!) b) Cl2 + 2NaI à I2 + 2NaCl Chlorine is above Iodine on the Activity series chart so a single replacement DOES occur. 3. See your own notes and the detailed notes posted on the website! The amount of energy produced or absorbed in a chemical reaction is directly proportional to the moles of product produced. Stoichiometry (mole ratios) affect the energy of a reaction. 4. No, both reactants will NOT be totally consumed. (In other words, this is a limiting and excess reagents problem) Products formed: 1.25 g FeS and 0.0286 g H2 5. a) 20.6 g Cu(NO3)2 and 51.6 g AgI b) CuI2 is the limiting reagent c) 1.7 g AgNO3 excess (note: depending on SF, you may have 1.6 g as an answer) d) 35.0 g + 39.0 g = 51.7 g + 20.6 g + 1.7 g Another way to show the check: 35.0 + (39.9 – 1.7) = 51.7 + 20.6 35.0 + 37.4 = 51.7 + 20.6 6. a) 49.0 g C2H5Cl b) 48.4 % YIELD 7. a) 250 g of UBr6 2 SF b) 140 g of U will theoretically produce 422 g of UBr6 and will actually produce 350 g of UBr6 8. 38.8% Ca 9. a) Empirical formula of glucose: CH2O 10. UBr3 or Uranium (III) Bromide is formed. 20.0% P 41.3% O b) Molecular formula of glucose: C6H12O6 GO back to your worksheets and practice each type of question that you have seen on this Practice test.