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ФФФФФФФФФ>ФФФФФФФФФ>ФФФФФФФФФ>Chop Here>ФФФФФФФФФ>ФФФФФФФФФ>ФФФФФФФФФ>ФФФФФФФФФ JARVIS COLLEGIATE INSTITUTE CHEMISTRY Grade 12. Time: 1 1/2 hours. 11.30 a.m. to 1:00 p.m. Tues June 20 1989 NAME HOME FORM Circle your teacher's name and indicate the period you take Chemistry. Marks. Part A = ___ Part B = ___ Total Marks = ___ 30 55 85 INSTRUCTIONS TO STUDENTS. 1. Answer Part A on the answer sheet at the bottom of page 5. DO NOT detach the answer sheet. 2. There is a periodic table at the back of the exam. You may detach this. 3. The questions in Part 1 are worth 1 mark each. 4. Answer all the questions from Part B in the given space. Part A. Answer all questions in Part A on the answer grid at the bottom of page 5. 1. Which of the following properties is not characteristic of metals? a) They are dull in appearance b) They are malleable c) They are ductile d) They are good conductors of heat. 2. The following is a list of the usual charge found on the ions of a series of elements: V3+ W2+ X+ Z2- Which elements are likely to be metals? a) V and W b) V, W and X. c) X and Y d) Y and Z 3. Which of the following is not a postulate of the kinetic molecular theory? a) There are no attractive forces between the molecules b) Gases consist of extremely small particles called molecules c) Molecules of different gases have the same average velocity at the same temperature d) All collisions of gas molecules are perfectly elastic 4. 2.00 L of dry hydrogen gas is collected at 27.0oC and 100 kPa pressure. The volume of this hydrogen measured at 227oC and 220 kPa pressure would be a) 2.00 x 220 x 27 L b) 2.00 x 100 x 300 L 100 227 220 500 c) 2.00 x 220 x 300 L d) 2.00 x 100 x 500 L 100 500 220 300 5. If the temperature of a fixed mass of gas is kept constant while the volume is decreased a) the average kinetic energy of the particles decreases b) the average kinetic energy of the particles increases c) the number of collisions per second increases d) the number of collisions per second decreases 6. The compound in the following list which is the best example of an ionic solid at room temperature is, a) calcium bromide (CaBr2) b) boron trifluoride (BF3) c) tetrachloromethane (CCl4) d) phosphorus(V) oxide (P2O5) 7. Which one of the following items correctly indicates both the correct electron dot (Lewis) diagram and the correct structural (line) diagrams for the molecules illustrated. H H a) CH4 H C H H C H H H b) NH3 H N N H N H H H c) CO2 :O::C::O: O C O d) H2O H O: H O H H 8. A metal which does NOT readily liberate hydrogen gas from cold water is a) magnesium b) sodium c) potassium d) calcium 9. 1.00 L of a particular gas, at STP, has a mass of 4.80 g. Its molar mass is a) 0.210 g b) 4.80 g c) 108 g d) 22.4 g 10 When the skeleton equation Al2(SO4)3 + Ca(OH)2 Al(OH)3 + CaSO4 is balanced with the smallest whole numbers, the coefficient of Ca(OH)2 is a) 1 b) 2 c) 3 d) 4 11 Which of the following statements describing the characteristics of the elements in the Periodic Table is TRUE? a) The sequence of the elements Si, P, Cl shows increasing metallic character. b) The sequence of the elements Li, Na, K shows decreasing metal character. c) The sequence of the elements C, N, O shows decreasing atomic radius. d) The sequence of the elements Ti, V, Cr shows increasing electropositivity. 12 In general the valence electrons of metals are a) few in number and weakly held b) few in number and strongly held b) many in number and weakly held d) many in number and strongly held 13 Successive ionization energies, in kJ/mol, for an unknown element are given below. E1 = 711 E2 = 1421 E3 = 7733 E4 = 9196 To which family of the Periodic Table does the element belong? a) IV b) III c) II d) I 14 Benzoic acid, C6H5COOH, is a component of candle wax. It burns according to the unbalanced equation: C6H5COOH + O2 CO2 + H2O When the equation is balanced for 1 mole of C6H5COOH the coefficient for oxygen is a) 6 1\2 b) 7 1/2 c) 8 1/2 d) 15 15 The reaction between gaseous hydrogen chloride and water is best represented by a) HCl(g) + H2O(l) H22+(aq) + Cl-(aq) b) HCl(g) + H2O(l) H2(g) + HClO(aq) c) HCl(g) + H2O(l) H+(aq) + ClO-(aq) d) HCl(g) + H2O(l) H3O+(aq) + Cl-(aq) 16 Which of the following will form an acidic solution when dissolved in water? a) CO2 b) Na2O c) O2 d) H2 17 The best example of a molecular solid in which the intermolecular bonding is only London dispersion forces is a) potassium iodide (KI) b) carbon dioxide (CO2) c) water (H20) d) ammonia (NH3) 18 The products formed when potassium hydroxide reacts with sulphuric acid are a) a salt and hydrogen b) sulphur dioxide and water c) a metallic oxide and water d) a salt and water 19 Which one of the following groups of elements will all produce acidic solutions when their oxides are dissolved in water? a) Cl S Br N b) S P Ca Na c) N Mg K Ni d) Li Mg Na Cu 20 Real gases behave most like ideal gases when a) the pressure is high and the temperature is low b) the pressure is low and the temperature is high c) the pressure is low and the temperature is low d) the pressure is high and the temperature is high 21 Equal masses of hydrogen and oxygen are placed in a sealed container. Which of the following statements about the system is TRUE? a) since there are more hydrogen molecules, the mass of the hydrogen is greater b) since both the hydrogen and the oxygen are at the same temperature both have the same average molecular velocity c) since the oxygen molecule is 16 times heavier than the hydrogen molecule, the hydrogen molecules are, on the average, moving 4 times faster than the oxygen molecules. d) since they are both at the same temperature , both exert the same pressure 22 2KClO3 2KCl + 3O2 How many moles of oxygen are produced during the decomposition of 8.0 mol of KClO3? a) 5.3 b) 24 c) 48 d) 12 23 Both copper metal and sodium chloride have high melting points. Solid copper conducts electricity well but sodium chloride will conduct electricity only when melted or dissolved in a polar solvent.The difference in electrical conductivity of the two solids is best explained by the a) stronger bonding forces between particles of NaCl than in Cu b) greater mobility of electrons in solid Cu than in solid NaCl c) greater number of atoms in a mole of NaCl than in a mole of Cu d) solubility of sodium chloride in water Questions 24, 25 and 26 refer to the following table which lists some properties of substances Substance . Melting . Electrical conductivity . Water Point (oC) in solid in liquid solubility A 776 low high high B -198 low low low C 961 high high low D 1640 low low low 24 Which substance is most likely to be an ionic solid? a) A b) B c) C d) D 25 Which substance is most likely to be a network solid a) A b) B c) C d) D 26 Which substance is most likely to be a metal a) A b) B c) C d) D 27 The number of moles of nitrogen gas present in 21 g of the gas is a) 0.67 b) 0.75 c) 1.3 d) 1.5 28 The density of carbon dioxide gas (relative molecular mass 44) at STP is a) 0.509 g/L b) 0.986 g/L c) 1.79 g/L d) 1.96 g/L 29 The concentration of NaOH in an aqueous solution containing 4.0 g of NaOH dissolved in 100 mL of solution is 30 Scientists prefer to measure quantities per mole rather than per gram because a) one mole of any substance has the same mass as a mole of any other substance b) the gram is too small a unit to be used in the laboratory c) a mole of any substance contains the same number of particles as a mole of any other substance d) a mole of any substance has the same volume as any other substance measured at STP. Part B. Answer all questions in this section in the blank spaces provided. 1. Name ANY FIVE of the following compounds. (l mark each). a) H2SO3(aq) __________________ b) (NH4)2SO4 ______________________ c) Fe(OH)3 __________________ d) Zn(CH3CO2)2 ________________ 5 e) SF6 ________________________ f) Ca(ClO)2 ____________________ g) Cu(NO3)2.6H2O ___________________________________________ 2. Write the formula for ANY FIVE of the following compounds. a) lead(II) phosphate ______________ b) potassium chlorate ______________ c) tetraphosphorus heptasulphide ______________ 5 d) nitrous acid ______________ e) magnesium hydrogen carbonate ______________ f) sodium periodate ______________ g) barium hydroxide octahydrate ______________ Part B is continued on page 6. ANSWERS TO PART "A". Answer each of the questions in Part A by writing the letter that corresponds to the most correct answer in each case in the brackets provided. USE CAPITAL (UPPER CASE) LETTERS ONLY. PART A. 1 ( ) 2 ( ) 3 ( ) 4 ( ) 5 ( ) 6 ( ) 7 ( ) 8 ( ) 9 ( ) 10 ( ) 11 ( ) 12 ( ) 13 ( ) 14 ( ) 15 ( ) 16 ( ) 17 ( ) 18 ( ) 19 ( ) 20 ( ) 21 ( ) 22 ( ) 23 ( ) 24 ( ) 25 ( ) 26 ( ) 27 ( ) 28 ( ) 29 ( ) 30 ( ) . 3. Write a balanced equation to represent each of the following reactions. a) The formation of a precipitate when aqueous solutions of calcium nitrate and aluminum sulphate are mixed. 3 _______________________________________________________________ b) The formation of carbon dioxide by the reaction of hydrochloric acid on marble (calcium carbonate). 3 _______________________________________________________________ 4. Draw an electron dot (Lewis) diagram for the following molecules:- a) NF3 b) O2 4 5. Draw Lewis structures (line representation) for molecules of:- a) Ethylene CH2CH2 b) HCN 4 PLEASE NOTE. IN QUESTIONS 6, 7 AND 8 THERE IS CHOICE. DO ONLY THE NUMBER OF QUESTIONS ASKED FOR. EXTRA ANSWERS WILL NOT BE MARKED SO BE SURE TO CROSS OUT ALL BUT THE SELECTIONS YOU WISH MARKED. 6. Answer any FOUR of the following questions. (2 marks each). a) In volumetric analysis the "Stoichiometric Point" and the "End Point" of a titration are rarely the same. Explain why this is so. b) How does the pH scale enable us to assess the acidity or the basicity of an aqueous solution? 8 . c) Equal volumes of acid A and acid B, both at the same concentration, were tested with a conductivity apparatus. The light bulb glowed brightly with acid B and only dimly for acid A. Comment on the relative strength of these two acids. Explain the observations. d) If a bottle of ammonia was spilled in a room its odour would eventually be detected throughout the room. Explain this observation in terms of kinetic molecular theory. e) How is water, a molecular substance, able to interact with, and dissolve, ionic solids? f) Explain the difference between temperature and heat. Illustrate your answer with an everyday example. g) What one feature of an element is the most important in deciding on its placement in a "Chemical Family"? Explain how this feature is illustrated in the "Alkali Metal" family. . h) If a half filled flask of water is sealed does the process of evaporation stop? Explain your answer. 7. Clearly explain ANY THREE of the following statements on the basis of chemical and physical concepts introduced in this years' course. (3 marks each). a) H2O and CO2 are both triatomic molecules, however, the H2O molecule is highly polar whereas the CO2 molecule is not. b) HOCl is acidic in aqueous solution but NaOH is basic when dissolved in water. 9 c) Adding crushed limestone (CaCO3) to lakes that have become acidified by acid rain can raise the pH of the water. d) Gasoline contains a very small amount of compounds of nitrogen but the emissions from automobile exhausts cause significant amounts of polluting oxides of nitrogen. . e) Why does the air that escapes from a car tire have a lower temperature than the air that is still in the tire but under pressure? f) Substances which are not ionic are often soft and pliable. 8. Calculate ANY FOUR of the following, showing all the steps involved in the calculation. (2 marks each). a) If a mixture containing 100 mL of propane (C3H8) and 1000 mL of oxygen is ignited and returned to room temperature and pressure what gases will remain and what volume will each gas occupy? Equation. C3H8 + 5O2 3CO2 + 4H2O. b) What volume of oxygen, measured at STP, is produced by the electrolytic decomposition of l kmol of Al2O3? Equation. 2Al2O3 4Al + 3O2 8 c) What is the mass of 5.0 L of freon-11 (CFCl3) measured at STP? d) What is the concentration of KOH in mol/L if 22.44 g of KOH is dissolved in enough water to make exactly 2 L of solution? e) The density of a gas is 2.41 g/L at STP what is the molecular mass of the gas? f) A scuba diver's tank has a volume of about 13 L. When fully charged with compressed air the pressure of the air in the tank is about 150 times greater than atmospheric pressure. When the air in the tank is released at atmospheric pressure and constant temperature what will be the volume of the air? 9. A welder's tank of compressed acetylene (C2H2) contains 3000 g of fuel. a) Calculate the mass of oxygen required for the complete combustion of all the acetylene in the tank given the following equation for the reaction. 2C2H2(g) + 5O2(g) 4CO2(g) + 2H2O(g) Clearly set out all steps in your calculation. 3 b) What volume of carbon dioxide will be produced at 900oC and 101.3kPa? Clearly show all steps in your calculation. 3