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Chem 120 Practice Final 02

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University of Waterloo
CHEM 120
Carey Bissonnette

Name: __________________________ Date: _____________ 1. Which one of the following statements about atomic structure is false? A) The electrons occupy a very large volume compared to the nucleus. B) Almost all of the mass of the atom is concentrated in the nucleus. C) The protons and neutrons in the nucleus are very tightly packed. D) The number of protons and the number of neutrons are always the same in the neutral atom. 2. Which of the experiments listed below did not provide the information stated about the nature of the atom? A) The Rutherford experiment proved that the Thomson "plum pudding" model of the atom was essentially correct. B) The Rutherford experiment determined the charge on the nucleus. C) Millikan's oil-drop experiment showed that the charge on any particle was a simple multiple of the charge on the electron. D) The cathode-ray tube proved that electrons have a negative charge. 3. The ion O has A) 8 protons, 8 neutrons, 8 electrons B) 8 protons, 8 neutrons, 10 electrons C) 8 protons, 8 neutrons, 2 electrons D) 8 protons, 8 neutrons, 10 electrons E) 8 protons, 16 neutrons, 8 electrons 4. ______ form ions with a 2+ charge when they react with nonmetals. A) Alkali metals B) Alkaline earth metals C) Halogens D) Noble gases E) None of these choices 5. Which of the following formulas is not correct? A) ZnSO 4 B) Ca(OH) 2 C) NaS D) KF E) NH Br4 Page 1 6. Which is the correct formula for gold(I) oxide? A) AuO B) Au O2 C) AuO 2 D) Au O2 2 E) Au O2 3 7. Which of the following is not the correct chemical formula for the compound named? A) Li O2 lithium oxide B) Fe2PO 4 iron(II) phosphate C) HCl hydrogen chloride D) CaBr 2 calcium bromide E) Zn3 2 zinc phosphide 8. The atomic mass of rhenium is 186.2. Given that 37.1% of natural rhenium is rhenium- 185, what is the other stable isotope? 183 A) 75Re 187 B) 75Re 189 C) 75Re 181 D) 75Re 190 E) 75Re 9. The average mass of a boron atom is 10.81. If you were able to isolate a single boron atom, what is the chance that you would randomly get an atom with mass 10.81? A) 0% B) 0.81% C) about 11% D) 10.81% E) greater than 50% Page 2 10. For which of the following compounds does 1.0 g represent 5.55 × 10 mol? A) NO 2 B) H O2 C) NH 3 D) C 2 6 E) NO 11. The mass of 0.82 mol of a diatomic molecule is 131.3 g. Identify the molecule. A) F 2 B) Cl 2 C) Br 2 D) I 2 E) Xe 12. NaHCO 3 is the active ingredient in baking soda. How many grams of oxygen are in 0.32 g of NaHCO 3 A) 0.011 g B) 1.0 g C) 0.061 g D) 0.0038 g E) 0.18 g 13. Compound X 2Y is 60% X by mass. Calculate the percent Y by mass of the compound X 2 2 A) 20% B) 30% C) 40% D) 60% E) 80% 14. An oxybromate compound, NaBrO x where x is a whole number, is analyzed and found to contain 52.95% Br by mass. What is x? A) 0 B) 1 C) 2 D) 3 E) 4 Page 3 15. The empirical formula of a group of compounds is CHCl. Lindane, a powerful insecticide, is a member of this group. The molar mass of lindane is 290.8. How many atoms of carbon does a molecule of lindane contain? A) 2 B) 3 C) 4 D) 6 E) 8 16. When the equation C 10+22 → 2O + H O2is b2lanced with the smallest set of integers, the sum of the coefficients is A) 4 B) 64 C) 75 D) 44 E) 53 17. When the following equation is balanced, what is the sum of the coefficients? Al2(SO 4 3 Ca(OH) →2Al(OH) + C3SO 4 A) 4 B) 9 C) 8 D) 3 E) 10 18. A 6.32-g sample of potassium chlorate was decomposed according to the following equation: 2KClO 3→ 2KCl + 3O 2 How many moles of oxygen are formed? A) 1.65 mol B) 0.051 mol C) 0.0344 mol D) 0.0774 mol E) none of these Page 4 19. 10.8 g of Al and 13.4 g of Br2react according to the following equation: 2Al + 3Br 2 2AlBr 3 What mass of AlBr is3formed, assuming 100% yield? A) 107 g B) 14.9 g C) 22.4 g D) 33.5 g E) 24.2 g 20. A 15-g sample of lithium is reacted with 15 g of fluorine to form lithium fluoride: 2Li + F 2 2LiF. After the reaction is complete, what will be present? A) 2.16 mol lithium fluoride only B) 0.789 mol lithium fluoride only C) 2.16 mol lithium fluoride and 0.395 mol fluorine D) 0.789 mol lithium fluoride and 1.37 mol lithium E) none of these 21. Which of the following solutions contains the greatest total ion concentration? A) One mole of potassium chloride dissolved in 1.0 L of solution. B) One mole of iron(II) nitrate dissolved in 1.0 L of solution. C) One mole of potassium hydroxide dissolved in 1.0 L of solution. D) One mole of sodium phosphate dissolved in 1.0 L of solution. E) At least two of these solutions have an equal number of ions, and these contain the greatest total ion concentration. 22. How many grams of Na SO 2re 4equired to make 150.0 mL of a 0.180 M sodium sulfate solution? A) 2.78 g B) 3.21 g C) 3.40 g D) 3.84 g E) none of these 23. A 51.24-g sample of Ba(OH) 2 is dissolved in enough water to make 1.20 L of solution. How many milliliters of this solution must be diluted with water in order to make 1.00 L of 0.100 molar Ba(OH) ? 2 A) 400. mL B) 333 mL C) 278 mL 3 D) 1.20 × 10 mL E) 249 mL Page 5 24. High concentrations of aqueous solutions of potassium sulfide and copper(II) nitrate are mixed together. Which statement is correct? A) Both KNO and C3S precipitate from solution. B) No precipitate forms. C) CuS will precipitate from solution. D) KNO will3precipitate from solution. E) No reaction will occur. 25. Lead(II) nitrate reacts with sodium chloride in aqueous solution to form a precipitate. What is the net ionic equation for this reaction? 2+ – A) Pb (aq) + 2NO (aq) 3 Pb(NO ) (s) 3 2 B) Na +(aq) + Cl (aq) → NaCl(s) 2+ – C) Pb (aq) + 2Cl (aq) → PbCl (s) 2 D) Na (aq) + NO (aq) → NaNO (s) 3 3 E) Na (aq) + Cl (aq) → Na Cl(s) 2 26. Select the unbalanced net ionic equation for the reaction between aqueous lead nitrate and aqueous potassium iodide. A) Pb(NO 3 2(aq) + KI(aq) → PbI (s) 2 KNO (aq) 3 2+ – + – 2+ – + – B) Pb (aq) + NO (aq) 3 K (aq) + I (aq) → Pb (aq) + I (aq) + K (aq) + NO (aq) 3 C) Pb (aq) + NO (aq) 3 K (aq) + I (aq) → PbI (s) + K (aq2 + NO (aq) 3– D) Pb (aq) + I (aq) → PbI (s) 2 E) none of these 27. You mix 50.0 mL of 2.00 M lead(II) nitrate with 50.0 mL of 2.00 M sodium chloride. What mass of lead(II) chloride should you form? A) 12.1 g B) 13.9 g C) 24.3 g D) 27.8 g E) none of these 28. A 0.350-g sample of an acid, HX, requires 25.4 mL of a 0.140 M NaOH solution for complete reaction. Calculate the molar mass of the acid. A) 42.3 g/mol B) 68.4 g/mol C) 98.4 g/mol D) 121.3 g/mol E) none of these Page 6 29. Which of the following statements is(are) true? Oxidation and reduction I. cannot occur independently of each other. II. accompany all chemical changes. III. describe the loss and gain of electron(s), respectively. IV. result in a change in the oxidation states of the species involved. A) I only B) II only C) III only D) IV only E) I, III, and IV 2- 30. What are the oxidation numbers of carbon in CO and2CO , res3ectively? A) +2, +6 B) +4, +6 C) -4, -4 D) -4, -6 E) +4, +4 31. In the following reaction, which species is the reducing agent? 3Cu + 6H ++ 2HNO → 3Cu + 2NO + 4H O 2 A) H + B) Cu C) N in NO D) Cu 2+ E) N in HNO 3 32. The following unbalanced reaction occurs in basic media: 2+ 2– 3+ 3+ Fe + Cr O2 7 → Fe + Cr The coefficient for water in the balanced equation is __________, and water appears on the __________ side of the equation. A) 7, left B) 7, right C) 14, left D) 14, right E) none of these Use the following to answer question 33: Samples of the gases H 2(g) and SO 2g) have equal masses and are at the same temperature and pressure. Calculate the following: Page 7 VH 33. The ratio of volumesV 2 SO 2 A) 1.0 B) 0.18 C) 32 D) 5.6 E) 180 34. A balloon contains 10.0 g of neon gas. With the temperature kept constant, 10.0 g of argon gas is added. What happens? A) The balloon doubles in volume. B) The volume of the balloon expands by more than 2 times. C) The volume of the balloon expands by less than 2 times. D) The balloon stays the same size, but the pressure increases. E) none of these 35. A sample of nitrogen gas has a volume of 160.0 mL at STP. What volume does the gas occupy if the absolute temperature and pressure are each quadrupled? A) 640.0 mL B) 40.00 mL C) 160.0 mL D) 400.0 mL E) 89.60 L 36. It is found that 250. mL of gas at STP has a mass of 1.00 g. What is the molar mass? A) 89.6 g/mol B) 28.0 g/mol C) 14.0 g/mol D) 22.4 g/mol E) none of these 37. Calculate the density of nitrogen at STP. A) 0.312 g/L B) 0.625 g/L C) 0.800 g/L D) 1.25 g/L E) 1.60 g/L Page 8 38. A 250.0-L cylinder contains 65.0% He(g) and 35.0% Kr(g) by mass at 25.0° C and 1.35 atm total pressure. What is the partial pressure of He in this container? A) 0.473 atm B) 0.675 atm C) 0.878 atm D) 1.32 atm E) 1.35 atm Use the following to answer question 39: Consider three 1.0-L flasks at STP. Flask A contains Ar gas, flask B contains 2 gas, and flask C contains H 2as. 39. In which flask do the gas particles have the lowest average kinetic energy? A) flask A B) flask B C) flask C D) The pas particles in all of the flasks have the same average kinetic energy. E) The gas particles in two of the flasks h
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