Practice Test. Moles & Stoich. Page What is the total number of nitrogen atoms in 0.25 mole of NO2 gas? (1)

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1 1. What is the total number of nitrogen atoms in 0.25 mole of NO2 gas? (1) (3) (2) (4) Which quantity of O2 contains exactly molecules? (1) mole (2) mole (3) 16.0 moles (4) 32.0 moles 3. Given the balanced equation representing a reaction: The mole ratio of to is (1) 1:1 (2) 1:3 (3) 3:1 (4) 3:7 4. Which chemical equation is correctly balanced? (1) H2(g) + O2(g) H2O(g) (2) N2(g) + H2(g) NH3(g) (3) 2NaCl(s) Na(s) + Cl2(g) (4) 2KCl(s) 2K(s) + Cl2(g) 5. During all chemical reactions, mass is (1) absorbed (2) conserved (3) formed (4) released 6. Which equation illustrates conservation of mass? (1) H2 + Cl2 HCl (2) H2 + Cl2 2 HCl (3) H2 + O2 H2O (4) H2 + O2 2 H2O 7. Which terms identify types of chemical reactions? (1) decomposition and sublimation (2) decomposition and synthesis (3) deposition and sublimation (4) deposition and synthesis 8. In which type of chemical reaction do two or more reactants combine to form one product, only? 10. The percent composition by mass of nitrogen in NH4OH (gram-formula mass = 35 grams/mole) is equal to (1) (2) (3) (4) 11. A hydrated salt is a solid that includes water molecules within its crystal structure. A student heated a 9.10-gram sample of a hydrated salt to a constant mass of 5.41 grams. What percent by mass of water did the salt contain? (1) 3.69% (2) 16.8% (3) 40.5% (4) 59.5% 12. A compound has an empirical formula of HCO2 and a molecular mass of 90. grams per mole. What is the molecular formula of this compound? (1) HCO (2) H2C2O4 (3) H4C4O8 (4) H6C6O The empirical formula of a compound is CH2O and the molecular mass is 180. What is the molecular formula of this compound? (1) C6H12O6 (2) C4H8O4 (3) C2H4O2 (4) CH2O 14. What is the total mass of 2.0 moles of H2(g)? (1) 1.0 g (2) 2.0 g (3) 3.0 g (4) 4.0 g 15. What is the total mass in grams of 0.75 mole of SO2? (1) 16 g (2) 24 g (3) 32 g (4) 48 g 16. What is the total number of moles of sulfur atoms in 1 mole of Fe2(SO4)3? (1) 1 (2) 15 (3) 3 (4) What is the gram-formula mass of (NH4)3PO4? (1) 112 g/mol (2) 121 g/mol (3) 149 g/mol (4) 242 g/mol (1) synthesis (2) decomposition (3) single replacement (4) double replacement 9. Which balanced equation represents a chemical change? (1) H2O( ) + energy H2O(g) (2) 2H2O( ) + energy 2H2(g) + O2(g) (3) H2O( ) H2O(s) + energy (4) H2O(g) H2O( ) + energy Page 1

2 18. Given the formula for a compound: Which molecular formula and empirical formula represent this compound? (1) C2HNO2 and CHNO (2) C2HNO2 and C2HNO2 (3) C4H2N2O4 and CHNO (4) C4H2N2O4 and C2HNO2 19. Which type of formula represents the simplest whole-number ratio of atoms of the elements in a compound? (1) molecular formula (2) condensed formula (3) empirical formula (4) structural formula 20. What is the total number of atoms contained in 2.00 moles of nickel? (1) 58.9 (2) 118 (3) (4) One mole of which substance contains a total of atoms? (1) Li (2) NH3 (3) O2 (4) CO2 22. A compound has the empirical formula NO2. Its molecular formula could be (1) NO2 (2) N2O (3) N4O2 (4) N4O4 23. Base your answer to the following question on the information below and on your knowledge of chemistry. A student made a copper bracelet by hammering a small copper bar into the desired shape. The bracelet has a mass of 30.1 grams and was at a temperature of 21 C in the classroom. After the student wore the bracelet, the bracelet reached a temperature of 33 C. Later, the student removed the bracelet and placed it on a desk at home, where it cooled from 33 C to 19 C. The specific heat capacity of copper is J/g K. Determine the number of moles of copper in the bracelet. Page 2

3 24. Base your answer to the following question on the information below and on your knowledge of chemistry. The nuts, bolts, and hinges that attach some gates to a playground fence can be made of iron. The iron can react with oxygen in the air. The unbalanced equation representing this reaction is shown below. Balance the equationfor the reaction, using the smallest whole-number coefficients. 25. Base your answer to the following question on the information below and on your knowledge of chemistry. Many breads are made by adding yeast to dough, causing the dough to rise. Yeast is a type of microorganism that produces the catalyst zymase, which converts glucose,, to ethanol and carbon dioxide gas. The balanced equation for this reaction is shown below. Determine the total mass of ethanol produced when 270. grams of glucose reacts completely to form ethanol and 132 grams of carbon dioxide. 26. Base your answer to the following question on the information below. The reaction between aluminum and an aqueous solution of copper(ii) sulfate is represented by the unbalanced equation below. Al (s) + CuSO4(aq) Al2(SO4)3(aq) + Cu(s) Determine the total mass of Cu produced when 1.08 grams of Al reacts completely with 9.58 grams of CuSO4 to produce 6.85 grams of Al2(SO4) Base your answer to the following question on the information below. The Solvay process is a multistep industrial process used to produce washing soda, Na2CO3(s). In the last step of the Solvay process, NaHCO3(s) is heated to 300 C, producing washing soda, water, and carbon dioxide. This reaction is represented by the balanced equation below. 2NaHCO3(s) + heat Na2CO3(s) + H2O(g) + CO2(g) Identify the type of chemical reaction represented by the equation. Page 3

4 28. Given the balanced equation representing a reaction: Determine the total number of moles of oxygen that react completely with moles of. 29. Base your answer to the following question on the following paragraph. A portable propane-fueled lantern contains a mesh silk bag coated with metal hydroxides. The primary metal hydroxide is yttrium hydroxide. When the silk bag is installed, it is ignited and burned away, leaving the metal hydroxide coating. The coating forms metal oxides that glow brightly when heated to a high temperature. During a test, a propane lantern is operated for three hours and consumes 5.0 moles of propane from the lantern s tank. The balanced equation below represents the combustion of propane. C3H8 + 5O2 3CO2 + 4H2O + energy Determine the total number of moles of CO2 produced during the lantern test. 30. Base your answer to the following question on the following information. A piece of magnesium ribbon is reacted with excess hydrochloric acid to produce aqueous magnesium chloride and hydrogen gas. The volume of the dry hydrogen gas produced is 45.6 milliliters. The temperature of the gas is 293 K, and the pressure is 99.5 kilopascals. Balance below using the smallest whole-number coefficients. Mg(s) + HCl(aq) MgCl2(aq) + H2(g) 31. Write the empirical formula for the compound C8H Identify the type of chemical reaction represented by this equation. Base your answers to questions 32 and 33 on the information below. Rust on an automobile door contains Fe2O3(s). The balanced equation representing one of the reactions between iron in the door of the automobile and oxygen in the atmosphere is given below. 4Fe(s) + 3O2(g) 2Fe2O3(s) 32. Determine the gram-formula mass of the product of this reaction. Page 4

5 34. Determine the percent composition by mass of oxygen in the compound C6H12O6 35. What is the mass of 4.76 moles of Na3PO4 (gram-formula mass = 164 grams/mole)? 36. Show a correct numerical setup for calculating the number of moles of CO2 (gram-formula mass = 44 g/mol) present in 11 grams of CO2. Base your answers to questions 37 through 39 on the information below and on your knowledge of chemistry. In 1828, Friedrich Wöhler produced urea when he heated a solution of ammonium cyanate. This reaction is represented by the balanced equation below. 37. Explain why this balanced equation represents a conservation of atoms. 38. Write an empirical formula for the product. 39. Determine the gram-formula mass of the product. 40. Given the unbalanced equation: NH3 + O2 HNO3 + H2O balance the equation using the smallest whole number coefficients. Page 5

6 Answer Key PRACTICE Exam mol or for any value from 0.47 mol to mol, inclusive, or for 0.5 mol g or for any value from g to g, inclusive g 27. decomposition 28. Examples: mol mol 30. Mg(s) + _2 _HCl(aq) MgCl2(aq) + H2(g) 31. C4H g/mol. 33. Examples: synthesis redox oxidation % g g or 37. There are the same number of atoms of each element on both sides of the equation. No atoms are lost or gained g/mol NH3 + 2 O2 1 HNO3 + 1 H2O Page 6