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AVOGADRO EXAM 2001 UNIVERSITY OF WATERLOO DEPARTMENT OF CHEMISTRY 17 MAY 2001 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 STUDENT RESPONSE sheet. Also fill in the corresponding circles below your 2. Print your school name and city on your STUDENT RESPONSE sheet. printed name. 3. Select, and enter on the STUDENT RESPONSE sheet, one of the following CODE numbers: 5. Now answer the exam questions. Indicate your choice on the STUDENT RESPONSE sheet by Code 1 Ontario, now studying grade 11 Chemistry in a nonsemestered school Code 2 Ontario, now studying grade 11 Chemistry in a semestered school Code 3 marking one letter beside the question number. •Mark only one answer for each question. •Questions are all of the same value. •There is a penalty (1/4 off) for each incorrect answer, but no penalty if you do not answer. Ontario, grade 11 Chemistry already completed •Questions are not in order of difficulty. Code 5 Manitoba or Saskatchewan high school student Code 6 Québec high school student just filling the oval. Code 8 Alberta or British Columbia high school student Be careful that any erasures are complete—make Code 9 New Brunswick, Newfoundland, Nova Scotia or Prince Edward Island high school student 6. Take care that you make firm, black pencil marks, the sheet white again. Code 10 Northwest Territories, Nunavut, or Yukon high school student Code 11 High school student outside Canada Code 12 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 AVOGADRO EXAM 2001 - ANSWERS 1 How many mm3 are there in one m3 ? A B C 2 4 10+6 Al3+ B B3+ C N3- D V3+ E Ne3- 10+3 10-3 E 10-9 Two students made independent measurements of the mass of an object using four different balances. Their results are shown below. Student A: 51.6 g, 50.8 g, 53.4 g, 49.3 g Average value: 51.3 g Student B: 50.1 g, 49.6 g, 51.0 g, 49.4 g Average value: 50.0 g 5 The true mass is exactly 51 g. Which statement is correct? A The results of Student A are more accurate but less precise. B The results of Student A are more accurate and more precise. C The results of Student B are more accurate and more precise. D The results of Student B are more accurate and less precise. 6 How many neutrons are there in one A 37 B 17 C 18 D 20 E 54 37Cl atom? In what region of the periodic table are the atoms with the smallest covalent atomic radii found? A upper left B lower left C upper right D lower right E upper centre None of the above statements is true. 7 3 A 10+9 D E Which monatomic ion has an atomic number of 13 and 10 electrons? The nucleus of any atom, except hydrogen, is made up of A only neutrons. B only protons. C equal numbers of electrons and protons. D equal numbers of protons and neutrons. E neutrons and protons. The first ionization energy of an isolated atom, X(g), is A the minimum energy required to remove an electron from X(g). B the maximum energy required to remove an electron from X(g). C the energy released when X acquires an electron to form X-(g). D the minimum energy required to remove an electron from X-(g) E the maximum energy required to remove an electron from X-(g). 2001 UNIVERSITY OF WATERLOO AVOGADRO EXAM /2 8 Which one of the following elements would you expect to be the most similar in chemical properties to oxygen? 12 A U-tube mercury manometer is open on the right arm and connected to a gas sample at the other arm as shown below. The atmospheric pressure is 101 kPa and the difference in levels of mercury is 20 cm. What is the pressure of the gas in the bulb? A carbon B nitrogen A 121 kPa C fluorine B 104 kPa D neon C 94 kPa E sulfur D 98 kPa E 128 kPa 760 mm Hg = 101 kPa gas 20 cm 9 Which of the following is not a mixture? A brass B sodium chloride C air D seawater E stainless steel 13 A 140-g sample of nitrogen gas in a rigid container exerts a pressure of 203 kPa at 127oC. What is the volume of the container? 10 Noble gases are usually unreactive but a few compounds of the noble gases have been synthesized. Which one of the following chemical bonds is least likely to form? A 82 L B 26 L R = 8.3145 kPa L K-1 mol-1 C 110 L N, 14.01 g mol-1 D 160 L 0oC = 273.15 K E 52 L A Xe-O B Xe-F C Xe-N D Kr-F A 16 g mol 1 E Ar-F B 19 g mol 1 C 40 g mol 1 D 80 g mol E none of the above 14 A 7.20-L flask contains 20.0 g of an unknown gas at a pressure of 104 kPa and a temperature of 87oC. What is the molar mass of the gas? 11 Which compound contains both covalent and ionic bonds? A HClO4 B CsCl C graphite D KCN E water Note: Some teachers commented that HClO4 has ionic and covalent bonds. To the best of our knowledge, pure HClO4 is a liquid comprised of molecules with no ionic bonds. The monohydrate, HClO4$H2O, + however, is an ionic solid comprised of H3O − and ClO4 ions. - -1 2001 UNIVERSITY OF WATERLOO AVOGADRO EXAM /3 15 What is the total pressure in a 4.55-L container if it contains 0.0410 mol O2, 0.173 mol N2 and 0.056 mol He, at a temperature of 167oC? 19 Which of the following has the lowest melting point? A CaO(s) B Si(s) C C6H12O6(s) A 250 kPa B 82.4 kPa C 217 kPa D NaNO3(s) D 0.0232 kPa E SiO2(s) E 2.14 kPa R = 8.3145 kPa L K-1 mol-1 0oC = 273.15 K 16 Which of the following gaseous compounds behaves most like an ideal gas at 298 K and 101 kPa? 20 What is the maximum mass of iron that can be recovered from 1.06 L of 0.20 M Fe2(SO4)3 solution? A 12 g Fe, 55.85 B 24 g S, 32.07 A NO B H2S C 6.0 g C HF D 80 g D N2 E 40 g E SO3 17 What is the correct formula of the stable compound that contains only aluminum and sulfate ions? A B 21 A compound of sulfur and phosphorus contains 72.13% sulfur by mass. What is the empirical formula of this compound? A P2S5 B P2S3 C PS3 D P2S E PS2 Al2S3 AlSO4 C Al3S2 D Al3(SO4)2 E Al2(SO4)3 18 Which of the following molecules is not planar? (The central atom is underlined and all other atoms are bonded to it.) O, 16.00 S, 32.07 P, 30.97 22 Magnesium burns in oxygen to produce magnesium oxide, MgO. If 5.0 moles of magnesium and 4.0 moles of oxygen react to produce as much MgO as possible, how much of the excess reactant remains? A SF4 A 1.0 mol Mg B BrF3 B 1.0 mol O2 C SO3 C 1.5 mol O2 D H2CO D 3.0 mol Mg E AlF3 E 0.5 mol Mg 2001 UNIVERSITY OF WATERLOO AVOGADRO EXAM /4 23 What volume of 12 M HCl(aq) solution is required for the preparation of 7.50 L of 0.10 M HCl(aq)? A 6.3 L B 63 mL C 0.16 L D 0.90 L E 9.0 mL 26 Gastric fluid in the human stomach has a pH of 1.2. What is [H+] in gastric fluid? A 1.2 mol L-1 B 0.12 mol L-1 C 12 mol L-1 D 15.8 mol L-1 E 0.063 mol L-1 24 Consider the unbalanced equation KMnO4 + HCl → KCl + MnCl2 + Cl2 + H2O. If the coefficient of KMnO4 in the balanced equation is taken to be 2, what is the coefficient of HCl ? A 8 B 16 C 4 D 2 E 5 27 Which of the following is the poorest conductor of electricity? A 1.0 M HCl(aq) B a saturated, aqueous solution of CCl4 C molten sodium chloride D 1.0 M NH3(aq) E solid platinum 28 Diamond and graphite are 25 What products result from adding solid calcium oxide to water? A calcium hydroxide B calcium hydroxide and hydrogen gas C calcium hydride and oxygen gas D calcium hydride and calcium hydroxide E calcium metal, hydrogen gas, and oxygen gas A stereoisomers. B enantiomers. C allotropes. D isotopes. E structural isomers. 29 In which reaction does a precipitate form? A AgNO3(aq) + NH4NO3(aq) → B NH4Cl(aq) + NaOH(aq) → C CuSO4(aq) + HNO3(aq) → D HNO3(aq) + KOH(aq) → E Fe(NO3)2(aq) + Na2S(aq) → 2001 UNIVERSITY OF WATERLOO AVOGADRO EXAM /5 30 What is the systematic, IUPAC name for Fe2O3 ? A B 34 What is the approximate bond angle in the H2O molecule? (Choose the closest value.) iron(III) oxide A 60o B 90o C 109o D 120o E 180o iron oxide C iron(II) oxide D iron (II) trioxide E iron trioxide 31 What is the oxidation number of chlorine in HClO2 ? A +5 B +3 C +7 D -1 E 0 35 What is the net ionic equation for the reaction that occurs when aqueous barium chloride reacts with aqueous sulfuric acid? 32 In the reaction, A BaCl2(aq) + H2SO4(aq) → BaSO4(s) + 2HCl(aq) B H+(aq) + Cl-(aq) → HCl(g) C Ba2+(aq) + SO 4 (aq) → BaSO4(s) D Br2(l) + 2OH-(aq) → OBr-(aq) + Br-(aq) + H2O(l) the reducing agent and the oxidizing agent are, respectively A Br2 and OH- B Br2 and Br- C OH- and Br2 D Br2 and Br2 E Br2 and OBr- E 2- 2Ba2+(aq) + 2Cl-(aq) + 2H+(aq) + SO 4 (aq) → BaSO4(aq) + 2HCl(g) 2- Ba2+(aq) + SO 4 (aq) → BaS(s) + 2O2(g) 36 The addition of HCl to C2H4 produces C2H5Cl. In a certain experiment, 5.61 grams of C2H4 reacts with excess HCl and 4.83 grams of C2H5Cl is recovered. What is the percent yield for the experiment? A 86.1% B 37.4% C, 12.01 C 20.0% Cl, 35.45 D 16.1% E 13.9% H, 1.01 33 Which molecule has a triple bond? A C2H2 B C2H4 C O2 D CO2 E N2H2 2001 UNIVERSITY OF WATERLOO AVOGADRO EXAM /6 40 A sample of water, initially at 25oC, was heated at a constant rate of 1.00 kJ per second until the temperature was 110oC. Which of the following graphs of temperature versus time best depicts the variation of temperature with time? 37 Which of the following is not endothermic? A CO2(s) → CO2(g) B Br2(l) → Br2(g) C O(g) + e- → O-(g) D H2(g) → 2H(g) A E LiF(s) → Li (g) + Cl-(g) + 38 Which of the following represents the ground electronic configuration of an isolated halogen atom? 2 1 A 1s 2s B 1s 2s 2p C 1s 2s 2p D 1s 2s 2p 3s 3p 4s 3d E 1s 2s 2p 3s 3p B 2 2 4 2 2 6 2 2 6 2 6 2 2 6 2 5 2 5 C 39 What is [Na+] when 35.0 mL of 0.284 M Na2SO4(aq) and 45.0 mL of 0.196 M NaNO3(aq) are mixed? Assume the final volume is 80.0 mL. A 0.234 mol L-1 B 0.172 mol L-1 C 0.248 mol L-1 D 0.359 mol L-1 E 0.382 mol L-1 D E 2001 UNIVERSITY OF WATERLOO AVOGADRO EXAM /7