CHEM 13 NEWS EXAM 2000

Transcription

1 HM 13 NWS XM 2000 UNIVRSITY OF WTRLOO PRTMNT OF HMISTRY 11 MY 2000 TIM: 75 MINUTS 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: 2. Print your school name and city on your STUNT RSPONS sheet. 3. Select, and enter on the STUNT RSPONS sheet, one of the following O numbers: ode 1 ode 2 ode 3 ode 4 ode 5 ode 6 ode 7 ode 8 ode 9 Ontario, now studying O hemistry in a nonsemestered school Ontario, now studying O hemistry in a semestered school Ontario, O hemistry already completed ny other Ontario student Manitoba or Saskatchewan high school student Québec high school student Québec GP student lberta or ritish olumbia high school student New runswick, Newfoundland, Nova Scotia, or Prince dward Island high school student ode 10 Northwest Territories, Nunavut, or Yukon high school student 4. Print your name (last name, first name and optional middle initial) on the STUNT RSPONS sheet. lso fill in the corresponding circles below your printed name. 5. Now answer the exam questions. Indicate your choice on the STUNT RSPONS 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. ode 11 High school student outside anada ode 12 Teacher H He Li e N O F Ne Na Mg l Si P S l r K a Sc Ti V r Mn Fe o Ni u Zn Ga Ge s Se r Kr Rb Sr Y Zr Nb Mo Tc Ru Rh Pd g d In Sn Sb Te I Xe s a La* Hf Ta W Re Os Ir Pt u Hg Tl Pb i Po t Rn Fr Ra c** * Lanthanides ** ctinides

2 1 How many isomeric alcohols have the molecular formula 4 H 10 O? 4 Which one of the following compounds is not very soluble in water? ethanoic acid ethanol ethanal chloroethane ethanamine 2 The reaction O O H 3 OH + H 3 OH H 3 O H 3 + H 2 O is an example of neutralization. hydrolysis. dehydration. esterification. combination. 5 Which of the following compounds is expected to have the highest boiling point? O H 3 H 3 O H H H H 3 H 3 H 2 H 2 OH HO H 2 H 2 OH 3 The molecule O H 3 H 2 O H H 2 OH NH 2 is an alcohol, amide, and ketone 6 What is the IUP name for the following compound? H 2 H 3 H 3 H H H H 3 r H 2 H 3 alcohol, amine, and ether ether, carboxylic acid, and amine ether, carboxylic acid, and amide amine, ketone, and alcohol 2-bromo-3,4-diethylpentane 2,3-diethyl-4-bromopentane 1-methyl-2,3-diethyl-3-bromobutane 2-bromo-3-ethyl-4-methylhexane 3-ethyl-4-methylhexyl bromide 2 / HM 13 NWS XM 2000 UNIVRSITY OF WTRLOO

3 7 Which compound is most likely to polymerize to form very large molecules (macromolecules)? H 2 =Hl HO OH OH H 2 H H 2 HO H 2 H 2 OH H 3 l 17 H 35 OOH 10 toms of element X form a binary compound with scandium having the formula Sc 2 X 3. The element X could be oxygen nitrogen hydrogen fluorine carbon 8 Which one of the following statements concerning benzene, 6 H 6, is not correct? The carbon atoms form a flat hexagon with bond angles of approximately 120 o. 11 ccording to the building-up principle (ufbau procedure), the ground-state electron configuration of Zr 2+ is 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 4p 6 5s 2 5p 6 6s 2 6p 2 Two equivalent Lewis structures (i.e. electron-dot structures) can be drawn for benzene. The double bonds in the benzene molecule oscillate rapidly back and forth between adjacent pairs of carbon atoms. enzene is an aromatic compound. 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 6 4d 2 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 6 5s 2 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 6 4f 2 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 6 5s 1 4d 1 The carbon atom in benzene is sp 2 hybridized. 9 The species 17 8O 2 has 12 In which one of these salts are the ions isoelectronic (i.e. the ions have the same number of electrons)? 8 protons 8 electrons 8 neutrons 6 electrons 6 protons Mgl 2 Mg 3 P 2 Nal MgO MgS 2000 UNIVRSITY OF WTRLOO HM 13 NWS XM / 3

4 13 In the Lewis structure for lf 3, the number of lone pairs of electrons around l, the central atom, is Given the following information, what is the standard enthalpy of formation for butane, 4 H 10 (g)? 4 H 10 (g) + 13 / 2 O 2 (g) 4 O 2 (g) + 5 H 2 O(g) H o H o f = kj/mol for O 2 (g) = kj/mol for H 2 O(g) = kj 14 Which one of the following pure compounds contains both ionic and covalent bonds? SiO 2 (s) NH 4 l(s) H 3 l(g) = kj/mol for H 2 O(l) kj/mol 345 kj/mol kj/mol graphite(s) kj/mol H 2 S(g) The answer cannot be determined because H o f for O 2 (g) is not given. 15 Which one of the following molecules is not planar? H 2 H 2 H 2 NNH 2 HNNH H 2 O F 3 18 t a certain temperature and pressure, the enthalpy of combustion of solid iron to form Fe 2 O 3 (s) is 822 kj per mole of Fe 2 O 3. The enthalpy of combustion of solid carbon to form O 2 (g) is 394 kj per mole of O 2. What is the enthalpy change at the same temperature and pressure for the reaction, 2 Fe 2 O 3 (s) + 3 (s) 4 Fe(s) + 3 O 2 (g)? 16 In liquid water, the strongest bonds between water molecules are 428 kj 462 kj ionic bonds 2106 kj covalent bonds kj Van der Waals bonds +462 kj hydrogen bonds metallic bonds 4 / HM 13 NWS XM 2000 UNIVRSITY OF WTRLOO

5 19 The rate law for the reaction X(aq) products 21 Which one of the following statements concerning catalysts is true? is Rate = k[x]. If it takes 55.5 minutes for [X] to decrease from 1.00 M to M, how long will it take for [X] to decrease from 1.00 M to M? 92.5 min 32.0 min catalyst increases the rate of the forward reaction only. dding a catalyst to an equilibrium mixture increases the concentration of products. catalyst lowers the enthalpy change for the reaction it catalyzes. 108 min catalyst increases the activation energy of a reaction min 77.7 min There is no net consumption of a catalyst, though it may be temporarily changed. 20 onsider the following reaction profile. Potential nergy (kj/mol) Tripling the Kelvin temperature of an ideal gas and doubling its pressure would change the volume of a 1.0-L sample to 6.0 L 1.5 L L 0.44 L Reaction oordinate 0.11 L Which of the following statements is/are correct? I. The activation energy for the forward reaction is 25 kj/mol. II. III. IV. The activation energy for the reverse reaction is 15 kj/mol. Increasing the temperature will increase the forward and reverse reaction rates by the same factor. The forward reaction is exothermic. 23 The density of a gas, assumed ideal, is 1.25 g/l at 273 K and kpa. What is the molar mass of this gas? The ideal gas constant is 44.0 g mol kpa L K -1 mol g mol g mol 1 II and III 32.0 g mol 1 I and III III and IV 42.1 g mol 1 I and IV II only 2000 UNIVRSITY OF WTRLOO HM 13 NWS XM / 5

6 24 For the gas phase reaction heat, 2 SO 2 (g) + O 2 (g) Ö 2 SO 3 (g) + which one of the following operations will increase the amount of SO 3 in the equilibrium mixture? 27 The acid used in lead storage batteries is sulfuric acid, H 2 SO 4 (molar mass, g mol 1 ). concentrated aqueous solution of H 2 SO 4 is 38.0% H 2 SO 4 (by mass) and has a density of 1.29 g/ml. What is the molar concentration of the solution? raising the temperature adding a catalyst decreasing the volume of the reaction vessel 3.0 mol L mol L mol L 1 increasing the reaction time 12 mol L 1 removing some oxygen 29 mol L L container of gas at 101 kpa and a 4.00-L container of gas at 152 kpa are connected by a tube of negligible volume. The valve between the flasks is opened and the gases mix at constant temperature. What is the final pressure, assuming and do not react? 28 What is the final ph of a solution obtained by mixing ml of M Hl and ml of M NaOH at 25 o? 1.88 K w = 1.0 x at 25 o 42 kpa 118 kpa 127 kpa 135 kpa 253 kpa The ph of a saturated solution of a(oh) 2 is at 25 o. What is K sp for a(oh) 2 (s)? 26 The phase diagram for a certain pure substance is shown below. The triple point is at 517 kpa and 57 o. What transition does this substance go through when the temperature is raised from 150 o to 50 o under a constant pressure of 400 kpa? vapourization sublimation condensation fusion Pressure Solid Liquid Gas Temperature K w = 1.0 x at 25 o atomization 6 / HM 13 NWS XM 2000 UNIVRSITY OF WTRLOO

7 30 basic aqueous solution contains the following ions. Which ion makes the solution basic? l 3+ NO 3 r NH 4 + F 33 xactly 3.0 mol NO and 2.0 mol O 2 were placed in a 1.00-L flask. These gases react as follows: 2 NO + O 2 Ö 2 NO 2. t equilibrium, the mixture contained 2.0 mol NO 2. What is the K c for the reaction above? What is the hydrogen ion concentration of rain water at 25 o if the ph is 5.50? K w = 1.0 x at 25 o 34 steady current of 25.0 amperes is passed through an aqueous solution of uso 4 for 32.2 minutes. What is the maximum mass of copper that can be deposited? mol L mol L 1 molar mass of u, 63.5 g mol 1 charge per mol e = coulombs 1 ampere = 1 coulomb / second mol L g mol L mol L g 31.8 g 63.6 g g 32 What volume of M o 2 (SO 4 ) 3 will contain mole of sulfate ions? 3.0 L L 35 If the following equation is balanced and written with the smallest whole number coefficients, what is the coefficient of HNO 2? MnO H + + HNO 2 Mn 2+ + H 2 O + NO L one 9.0 L two 0.11 L three four five 2000 UNIVRSITY OF WTRLOO HM 13 NWS XM / 7

8 36 galvanic cell is composed of a zinc metal electrode in a 1.0 M Zn(NO 3 ) 2 solution and a nickel metal electrode in a 1.0 M Ni(NO 3 ) 2 solution. The two half-cells are connected by a salt bridge and the two electrodes are connected by a wire. The temperature is 25 o. o = 0.24 V for Ni e - Ni(s) o = 0.76 V for Zn e - Zn(s) Which one of the following statements is correct? 39 W, X, Y, and Z represent different neutral second row atoms. Lewis symbols (i.e. electron dot structures) for these four atoms are shown below. Which atoms will combine in a four-to-one ratio? W X Y Z W and X lectrons flow from the nickel electrode through the wire to the zinc electrode. Positive ions in the salt bridge migrate towards the nickel half-cell. W and Y W and Z X and Y No reaction occurs. X and Z The standard cell potential is 1.00 V. The zinc electrode is the cathode. 37 In the reaction XeF 2 + ro H2 O Xe + 2 HF + ro - 4 xenon is oxidized, oxygen is reduced. xenon is reduced, bromine is oxidized. 40 solution containing both a 2+ and a 2+ ions will be treated with Na 2 ro 4 in an attempt to separate the ions by precipitation. If the initial concentrations of a 2+ and a 2+ are M and 0.20 M, respectively, how much Na 2 ro 4 should be added to 1.0 L of the solution to maximize the separation of a 2+ and a 2+? fluorine is reduced, bromine is oxidized. K sp = for aro4 xenon is reduced, fluorine is oxidized. K sp = for aro4 bromine is reduced, xenon is oxidized mol 38 Two wires are connected to a battery and a light bulb in series. When the free ends of the wires are dipped into a beaker of water, the bulb remains unlit. substance was then dissolved in the water but the bulb remains unlit. Which substance was added? HNO mol mol mol mol H 2 SO 4 Kl 2 H 5 OH NaOH 8 / HM 13 NWS XM 2000 UNIVRSITY OF WTRLOO