AVOGADRO EXAM 2000 UNIVERSITY OF WATERLOO DEPARTMENT OF CHEMISTRY 18 MAY 2000 TIME: 75 MINUTES

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Lambert Blake Goodwin
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1 VGR XM 2000 UIVRSITY F WTRL PRTMT F HMISTRY 18 MY 2000 TIM: 75 MIUTS This exam is being written by several thousand students. Please be sure that you follow the instructions below. 1. Print your name here: We'll send you a report on your performance. Top performers are eligible for a prize. 2. Print your school name and city on your STUT RSPS sheet. 3. Select, and enter on the STUT RSPS sheet, one of the following numbers: ode 1 ode 2 ode 3 ode 5 ode 6 ode 8 ode 9 ntario, now studying grade 11 hemistry in a nonsemestered school ntario, now studying grade 11 hemistry in a semestered school ntario, grade 11 hemistry already completed Manitoba or Saskatchewan high school student Québec high school student lberta or ritish olumbia high school student ew runswick, ewfoundland, ova Scotia or Prince dward Island high school student ode 10 orthwest Territories, unavut, or Yukon high school student ode 11 High school student outside anada ode 12 Teacher 4. Print your name (last name, first name and optional middle initial) on the STUT RSPS sheet. lso fill in the corresponding circles below your printed name. 5. ow answer the exam questions. Indicate your choice on the STUT RSPS sheet by 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. Questions are not in order of difficulty. 6. Take care that you make firm, black pencil marks, just filling the oval. e careful that any erasures are complete make the sheet white again. H He Li e F e a Mg l Si P S l r K a Sc Ti V r Mn Fe o i u Zn Ga Ge s Se r Kr Rb Sr Y Zr b Mo Tc Ru Rh Pd g d In Sn Sb Te I Xe s a La* Hf Ta W Re s Ir Pt u Hg Tl Pb i Po t Rn Fr Ra c** * Lanthanides ** ctinides

2 1 What volume of F 2 (g) must react with excess r 2 (g) to give 2.46 L of rf 5 (g)? 2.46 L 6.15 L L 12.3 L L 4 mixture of al 2 and a( 3 ) 2, with a total mass of 2.00 g, is dissolved in water and treated with excess g 3 solution. The precipitate (gl) is dried and found to weigh g. How much al 2 was in the original mixture? 1.00 g g 2.00 g g al 2 a( 3 ) 2 gl Molar masses g/mol g/mol g/mol 2 In which one of the following compounds is the oxidation state of chlorine the most positive? 1.33 g Hl 5 Which of the following involves a chemical change? l 2 al Hl 3 rl 3 compound contains only, H, and. nalysis shows that the compound is 75.9% by mass and 17.7% by mass. What is the empirical formula of the compound? Molar masses 3 H 4 4 H g/mol g/mol H 1.01 g/mol (1) evaporation (3) oxidation (2) neutralization (4) sublimation (1), (2), (3), and (4) (1) and (3) (2) and (3) (1) only (2), (3), and (4) 6 What value of x is required to balance the reaction e x H 2 3 e(h) H 3? 5 H H H UIVRSITY F WTRL VGR XM / 2

3 7 Suppose 6.0 mol 2 and 8.0 mol 2 react via to produce as much 2 as possible. Which one of the following statements is correct? 10 Identify the element X from the following information. (i) t 25 o and 101 kpa, it is a liquid. (ii) The formula of its sodium salt is ax. (iii) Its gas phase molecules have the formula X mol 2 remains The element X could be 0.67 mol 2 remains mercury 0.33 mol 2 remains hydrogen 0.67 mol 2 remains nitrogen 4.0 mol 2 and 5.0 mol 2 remain sulfur bromine 8 Which one of the following reactions, when carried out in aqueous solution, produces a precipitate? 11 The correct formula for sodium nitrate is H 2 S KH a 3 al 2 + a 2 3 a 2 H 4 l + K 2 S 4 a H 3 + ah 2 ah + H 2 S a 3 a 2 9 In the reaction g 3 (aq) + Hl(aq) H 3 (aq) + gl(s), 12 opper(ii) oxide reacts with hydrogen gas, producing copper metal and water. What is the correct chemical equation for this reaction? the spectator ions are u 2 2 (s) + 2 H 2 (g) 2 u(s) + 2 H 2 (l) g + and 3 u(s) + H 2 (g) u(s) + H 2 (l) H + and l - H + and 3 g + and l - u 2 (s) + 2 H(g) 2 u(s) + H 2 (l) u(s) + 2 H(g) u(s) + H 2 (l) u 2 (s) + 2 H 2 (g) u(s) + 2 H 2 (l) 3 and l UIVRSITY F WTRL VGR XM / 3

4 13 The space shuttle maneuvers in outer space using thrusters that obtain their energy from the reaction between hydrazine ( 2 H 4 ) and dinitrogen tetroxide ( 2 4 ). The equation for the reaction is 3 2 H 4 (l) (l) 4 2 (g) + 4 H 2 (g) + 2 H 2 (g) 16 n 11.3-g sample of gas occupies a volume of 3.56 L at STP. The molar mass of this gas is 3.17 g/mol 11.3 g/mol The ideal gas constant is kpa L -1 K -1 mol -1. and H is 1310 kj per mole of 2 4. How much energy is produced per mole of hydrazine? 13.6 kj 40.9 kj 40.2 g/mol 71.1 g/mol 79.7 g/mol 437 kj 17 Which of the following statements are true? 1310 kj 3930 kj 14 gas in a flask has a pressure of 193 kpa at 0 o. What is the pressure at 300 o if the volume of the flask remains constant? 405 kpa (i) (ii) (iii) (iv) t a given temperature, He atoms move faster than r atoms. The volume of 1.00 mol 2 gas is only twothirds the volume of 1.00 mol 3 gas, at the same temperature and pressure. The volume of 1.00 mol of ideal gas is always 22.4 L. In an equimolar mixture of He and r gases, helium and argon exert the same pressure kpa (i) and (ii) 493 kpa (i) and (iii) 223 kpa (ii) and (iv) 2509 kpa (ii) and (iii) 15 What is the ratio of oxygen atoms to hydrogen atoms in the mineral cacoxenite, Fe 4 (P 4 ) 3 (H) 3 $12H 2? 1:1 5:1 19:27 27:15 15:27 (i) and (iv) 18 What mass of solid sodium hydroxide is required to prepare 2.00 L of a 3.00 M solution? 40 g 80 g 240 g 480 g 667 g Molar Masses H 1.0 g/mol a 23.0 g/mol 16.0 g/mol 2000 UIVRSITY F WTRL VGR XM / 4

5 19 sample of water containing temporary hardness was boiled for a few minutes, then cooled and filtered. The formula of the compound left on the filter paper is most likely a 3 a(h 3 ) 2 as 4 al 2 Mg(H 3 ) 2 22 Sulfide ores are one of the principal sources of industrial metals. Which of the following metals does not occur in substantial quantities as a sulfide ore? copper nickel magnesium mercury zinc 20 n aqueous solution was thought to contain a high concentration of chloride ions. To confirm the presence of chloride ions a chemist would probably add a solution of 23 n aqueous solution of ph 0.0 at 25 o is slightly acidic. strongly acidic. barium chloride neutral. sodium nitrate slightly basic. sodium sulfate strongly basic. silver chloride silver nitrate 21 Which of the following metals will react readily with each of (i) cold water (ii) oxygen (iii) dilute acid? 24 omplete neutralization of 60 ml of 1.0 M hydrochloric acid solution requires 80 ml of sodium hydroxide solution. What is the molar concentration of the sodium hydroxide solution? 1.0 mol/l a 1.5 mol/l Mg 1.3 mol/l Pb 0.75 mol/l u 2.7 mol/l Ti 2000 UIVRSITY F WTRL VGR XM / 5

6 25 Water is a liquid at room temperature, whereas hydrogen sulfide is a gas. This is because 28 Which of the following represents the ground-state electron configuration of an alkali metal? the H bond is stronger than the S H bond. the H 2 molecule has a permanent dipole moment but the H 2 S molecule does not. the hybridization of in the H 2 molecule is different from that of S in the H 2 S molecule. the high electronegativity of leads to strong hydrogen bonding. oxygen has a smaller ionic radius. 1s 2 2s 2 2p 5 1s 2 2s 2 2p 6 1s 2 2s 1 2p 6 3s 1 1s 2 2s 2 2p 6 3s 1 1s 2 2s 2 2p 6 3s 2 29 Which of the following has the greatest bond energy? 26 When two elements unite to form an ionic crystal, what is the principal force that holds the particles together? HF Hl electrostatic attraction Hr Van der Waals forces HI metallic bonding Ht covalent attraction resonance 30 What is the electron dot diagram for the nitrogen atom? 27 Which one of the following groups forms an isoelectronic series? V 2+, V 3+, V 4+ S 2-, l -, r F -, l -, r - o 2+, i 2+, Zn 2+ l 3+, Si 3+, P 3+ * 2000 UIVRSITY F WTRL VGR XM / 6

7 31 The ground-state electron configuration of r 2+ is 1s 2 2s 2 2p 6 3s 2 3p 3 1s 2 2s 2 2p 6 3s 2 3p 6 3d 4 1s 2 2s 2 2p 6 3s 2 3p 6 3d 4 4s 1 1s 2 2s 2 2p 6 3s 2 3p 6 3d 5 4s 1 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 4p Which describes the atomic structure of r? protons, 81 neutrons, 36 electrons 36 protons, 45 neutrons, 37 electrons 46 protons, 35 neutrons, 47 electrons 35 protons, 46 neutrons, 34 electrons 35 protons, 46 neutrons, 36 electrons 32 lectronegativity is a measure of the electron affinity of an atom, ion or molecule. the electromotive force developed between an element and a solution of its salt. 35 Isotopes of an element have different atomic numbers. different numbers of electrons. the energy acquired or released in the formation of an anion. the affinity between the neutrons and electrons. the same atomic number and mass number. the same mass numbers but different atomic numbers. the power of an atom in a molecule to attract electrons. the same atomic numbers but different mass numbers. 33 For the reaction 2H + 2I + 5S the reducing agent is H I 5S H 36 The amount of fissionable plutonium that is being used by tomic nergy of anada in a test burn in its thermonuclear reactor is closest to 2 mg 200 mg 20 g THIS QUSTI WS LT. I 3-2 kg 2 S kg I 2 2 S UIVRSITY F WTRL VGR XM / 7

8 37 The electron dot diagram for carbon dioxide is 39 The chemical properties of element 19 will most closely resemble those of element 9. element 11. element 18. element 20. element The percent by mass of fluorine in calcium fluoride is 64.32% 48.67% a F Molar Masses g/mol g/mol 38 The decomposition of Pl 5 is described by the chemical equation Pl 5 Pl 3 + l % 24.33% 19.16% In an experiment, 1.5 grams of l 2 was obtained from 5.0 grams of Pl 5. What was the percent yield? less than 5% 6.8% 30% P l Molar Masses g/mol g/mol 88% greater than 90% 2000 UIVRSITY F WTRL VGR XM / 8

Carefully detach the last page. It is the Data Sheet.

Carefully detach the last page. It is the Data Sheet. M 13 WS XM 2009 UIVRSITY F WTRL PRTMT F MISTRY 14 MY 2009 TIM: 75 MIUTS This exam is being written by several thousand students. Please be sure that you follow the instructions below. We'll send you a