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AVOGADRO EXAM 1994 UNIVERSITY OF WATERLOO DEPARTMENT OF CHEMISTRY 19 MAY 1994 TIME: 75 MINUTES This exam is being written by several thousand students. Please be sure that you follow the instructions below. We'll send you a report on your performance. Top performers are eligible for a prize. 1. Print your name here: 4. Print your name (last name, first name and optional middle initial) on the ANSWER sheet. Also fill in the corresponding circles below your printed name. 2. Print your school name and city on your ANSWER sheet. 3. Select, and enter on the front of the ANSWER sheet, one of the following CODE numbers: 5. In the box headed EXAMINATION select Avogadro. 6. Now answer the exam questions. Indicate your choice on the Answer sheet by marking one letter beside the question Code 1 Ontario, now studying grade 11 Chemistry in number. a nonsemestered school • Mark only one answer for each question. Code 2 Ontario, now studying grade 11 Chemistry in • Questions are all of the same value. a semestered school • There is a penalty (1/4 off) for each incorrect Code 3 Ontario, grade 11 Chemistry already answer, but no penalty if you do not answer. completed • Questions are not in order of difficulty. Code 5 British Columbia, Alberta, Saskatchewan or Manitoba high school student 7. Take care that you make firm, black pencil marks, just filling Code 6 Québec high school student the circle. Code 8 Newfoundland, Prince Edward Island, Nova Scotia or New Brunswick high school student Be careful that any erasures are complete - make the sheet Code 9 High school student outside Canada Code 10 white again. Teacher H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe Cs Ba La* Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn Fr Ra Ac** * Lanthanides ** Actinides 1. Which element is NOT in the same group as neon? A Argon B Boron C Krypton D Radon E Xenon 4. In the periodic table, the elements are arranged in order of increasing A Number of neutrons B Number of protons C Ionization energy D Density E Electronegativity 2. Which terms on the left correctly match the materials on the right? 5. Select the element that is a typical nonmetal: Q Mechanical mixture X Salt water R Solution Y Carbon dioxide T Pure substance Z Washing detergent A Silver B Calcium C Chromium A QX, RY, TZ D Sulfur B QX, RZ, TY E Einsteinium C QY, RX, TZ D QZ, RX, TY E QZ, RY, TX 6. Choose the element that is a solid at room temperature and pressure: 3. Two particles with equal numbers of positive charges repel each other with a force, F. If the distance between the particles is doubled, the new repulsive force will be A F/4 B F/2 C F D 2F E 4F 2 / AVOGADRO EXAM 1994 UNIVERSITY OF WATERLOO A Argon B Bromine C Chlorine D Selenium E Krypton 7. Which molecule shows covalent bonding, with the 10. The following electronic configuration applies to an neutral atom or a cation: least ionic character? 1s2 2s2 2p6 3s2 3p6 4s1 A F− − Be− −F B F− − Li A An argon ion C F− − Br B A neutral potassium atom D F− −F C A chloride ion E F− − O− −F D A neutral calcium atom E A strontium ion The element or ion could be 8. Which pair of characteristics applies to typical ionic solids? A Good electrical conductivity and high ionization energy B High melting point and malleability C High melting point and crystalline structure D Low melting point and high heat conductivity E Low melting point and low aqueous solubility 11. What volume of hydrogen will have nearly the same number of molecules as 1.00 L of nitrogen gas, if both are measured at the same temperature and pressure? A 0.500 L hydrogen B 1.00 L hydrogen C 2.00 L hydrogen D 14.0 L hydrogen E 28.0 L hydrogen 9. Which neutral halogen atom has the smallest ionization energy for the first electron removed? 12. At what temperature is the average kinetic energy A Fluorine B Chlorine C Bromine D Iodine E Astatine of molecules in a gas twice as great as at O°C? A 1092 K B 746 K C 546 K D 273 K E 137 K 1994 UNIVERSITY OF WATERLOO AVOGADRO EXAM / 3 13. Pure oxygen gas in a closed container of fixed 16. If the following equation is obeyed, how many moles of ammonia are needed to produce 801 mol of hydrogen, H2? volume is heated until the average energy of the gas molecules is doubled. Which other aspect of this system is also doubled? → N2(g) + 3 H2(g) 2 NH3(g) A The density of the oxygen A 2.00 mol B The average velocity of the oxygen molecules B C The density of the oxygen gas C 267 mol D The pressure in the container D 534 mol E The volume occupied by each oxygen molecule E 1203 mol 22.4 mol 17. Hydrogen gas is a product in one of the following 14. What volume of argon gas at 100 kPa and 25°C must be added to a 1.00-Litre glass flask containing nitrogen gas at 70 kPa and 25°C to give a mixture of gases having a total pressure of 210 kPa at 25°C? cases. Which one? A Aluminum turnings are heated with hot, concentrated potassium hydroxide solution B Aqueous hydrogen peroxide is added to an aqueous solution of iron(III) nitrate C Solid sodium carbonate is added to dilute, aqueous hydrochloric acid A 1.40 L B 1.70 L C 2.00 L D Copper is placed in dilute, aqueous nitric acid D 2.86 L E Calcium oxide is warmed with ammonium chloride E 3.10 L 18. Which atom or ion is formed as a result of 15. In which of the following substances, all at reduction in the following reaction? 100 kPa, is the average translational energy of the molecules the greatest? 2 KMnO4 + 16 HCl → 2 KCl + 2 MnCl2 + 5 Cl2 + 8 H2O A Iron at 150°C A Potassium in KCl B Oxygen at 100°C B Manganese in MnCl2 C Liquid water at 80°C C Hydrogen in H2O D Carbon dioxide at 70°C D Chlorine in Cl2 E Ice at 0°C E Oxygen in H2O 4 / AVOGADRO EXAM 1994 UNIVERSITY OF WATERLOO 19. What is the missing term, X, in the following 22. Which one of the following aqueous reagents will most effectively remove carbon dioxide from an air sample? chemical equation? 238 U → 92 234 Th + X 90 A A positron A Amonium nitrate solution B A proton B Silica gel C A neutron C Concentrated sulfuric acid D A helium nucleus D Sodium hydroxide solution E An electron E Sodium hydrogen carbonate solution 23. What products will result from adding solid barium oxide to water? 20. Which set of oxidation numbers is correct for K2Cr2O7? A A solution of barium hydroxide A K +1; Cr +2.5; O −1 B Barium ions and hydrogen gas B K +4; Cr +3; O −2 C Barium ions and oxygen gas C K +1, Cr +6; O −2 D Barium metal and hydrogen gas D K +2; Cr +12; O −14 E No chemical change will take place E K +1; Cr +7; O −2 24. The general formula for the binary hydrogen compounds of the elements, E, of the nitrogen group of the periodic table is 21. The main gaseous product of the reaction of aqueous hydrochloric acid with manganese dioxide is A EH5 B EH4 A Permanganic acid C EH3 B Hydrogen D EH2 C Chlorine E E2H6 D Oxygen E Manganese chloride 1994 UNIVERSITY OF WATERLOO AVOGADRO EXAM / 5 25. The percentage, by mass, of oxygen in 28. The relative molecular mass of a gas is 56.0, and its simplest formula is CH2. What is the correct molecular formula for the gas? pitchblende, U3O8, is Relative atomic masses: O, 16.00; U, 238 A 72.7% B 35.0% C 30.4% D 17.9% E 15.2% Relative atomic masses: 26. How many moles of H2O are there in 1.8 L of A CH2 B C2H4 C C3H6 D C4H8 E C6H12 111 mol B 100 mol C 55.5 mol D 18 mol E the addition of 0.0500 mol/L KOH. What is the hydrogen ion concentration after 50.0 mL of KOH solution has been added? 1.8 mol 27. An oxide of nitrogen contains 30.4% nitrogen, by A 6.5 x 10−3 mol/L B 3.3 x 10−3 mol/L C 0.0311 mol/L D 0.0200 mol/L E 0.0120 mol/L 30. If, suddenly, 10.0% of the hydrogen (H) atoms on Earth became deuterium (D) atoms, what would be the new relative atomic mass for the element hydrogen? mass, and its relative molecular mass is near 90. Which oxide of nitrogen is it? Relative atomic masses: H, 1.01; N, 14.0; O, 16.0 Relative atomic masses: H, 1.008; D, 2.014 A N2O5 A 1.008 B N2O4 B 1.109 C N3O3 C 1.210 D N4O2 D 1.512 E NH4NO3 E 2.014 6 / AVOGADRO EXAM H, 1.0 29. 40.0 mL of 0.0700 mol/L aqueous HBr is titrated by water? A C, 12.0; 1994 UNIVERSITY OF WATERLOO 31. What mass of dry NaCl should one use to make 34. If one drop (0.05 mL) of 2.0 mol/L aqueous hydrochloric acid is added to 1.00 L pure water, the hydrogen ion concentration in the solution after mixing will be 2.00 L of a 0.147 mol/L sodium ion solution? Relative atomic masses: Na, 23.0; Cl, 35.5 A B 117 g C 17.2 g D 10.4 g E A 1.0 x 10−2 mol/L B 1.0 x 10−3 mol/L C 1.0 x 10−4 mol/L D 1.0 x 10−5 mol/L E 1.0 x 10−6 mol/L 28.3 g 5.22 g 32. If 4.0 g of sodium hydroxide is dissolved in enough water to make 400 mL of solution, what is the molar concentration of the solution? 35. By addition to water, 30.0 mL of 6.00 mol/L sulfuric acid is diluted to 150.0 mL. What is the concentration of sulfuric acid after dilution? Relative atomic masses: H, 1.01; O, 16.0; Na, 23.0 A 1.20 mol/L A 10.0 mol/L B 1.50 mol/L B 0.40 mol/L C 2.40 mol/L C 0.25 mol/L D 3.00 mol/L D 0.040 mol/L E 4.80 mol/L E 0.010 mol/L 36. AB2 is the salt of a strong acid and a strong base. A 0.020 mol/L solution of this salt is a saturated solution at 25°C. What is the concentration of B− ions in solution? 33. Sodium hypochlorite is prepared by the reaction 2 NaOH + Cl2 → NaCl + NaClO + H2O If 71 g of chlorine, Cl2, is bubbled into a solution containing 50 g of sodium hydroxide, which component limits the quantity of sodium hypochlorite formed? A 1.0 x 10−7 mol/L B 4.0 x 10−4 mol/L C 1.0 x 10−3 mol/L Relative atomic masses: H, 1.01; O, 16.0; Na, 23.0; Cl, 35.5 D 2.0 x 10−2 mol/L E 4.0 x 10−2 mol/L A Cl2 B NaCl C H2O D NaOH E NaClO 1994 UNIVERSITY OF WATERLOO AVOGADRO EXAM / 7 37. Choose the one pair of salts whose aqueous solutions would, upon mixing, create a precipitate. 39. Select the one ion or molecule that is NOT tetrahedral A Na2SO4 and (NH4)2S B NaNO3 and MgBr2 A NH4+ C Ag2SO4 and KNO3 B CH4 D CuSO4 and CaCl2 C SiCl4 E (NH4)2CO3 and KNO3 D PCl+4 E TeCl−4 38. Which of the following is the most acidic? 40. Which quantity of lead metal has the greatest mass? A Drinking water B Human saliva A 22.4 mol C Cow's milk B 1.0 mL D Human gastric juice C E Seawater D E 207.2 g 6.0 x 1023 atoms One formula mass expressed in grams THE END 8 / AVOGADRO EXAM 1994 UNIVERSITY OF WATERLOO