CHEM 115 Fall 2012 Bell Examination 3 Tuesday October 23 USE THE BACK PAGES AS SCRAP PAPER Useful information 1 cal 4 184 J C 3 00x108 ms 1 h 6 626x10 34 J s cH2O 4 148 J g K R 1 096776x107 m 1 1 J 1 kg m2 s Ans B Difficulty M H 198 9 kJ O3 g 1 5O2 g H 142 3 kJ O2 g 2O g H 495 0 kJ 1 Calculate the enthalpy change for the reaction NO g O g NO2 g from the following data NO g O3 g NO2 g O2 g A 551 6 kJ B 304 1 kJ C 190 9 kJ D 153 8 kJ E 438 4 kJ 2 Balance the following redox equation using the smallest integers possible and select the correct coefficient for the iron II hydroxide Fe OH 2 2 aq Fe2O3 s Cr OH 4 Fe OH 2 s CrO4 A 1 B 2 C 3 D 4 E 6 3 The Bohr theory of the hydrogen atom predicts the energy difference in J between the n 3 and the n 5 state to be aq H2O l OH aq Ans E Difficulty M 8 72 10 20 J 1 36 10 19 J 2 42 10 19 J A B C Ans D Difficulty E D E 1 55 10 19 J 1 09 10 18 J 2212111 R nn 1822initialfinal11 E 2 18x10J nn h mu 4 Cold packs whose temperatures are lowered when ammonium nitrate dissolves in water are carried by athletic trainers when transporting ice is not possible Which of the following is true of this reaction A H 0 process is exothermic B H 0 process is exothermic C H 0 process is endothermic Ans D Difficulty E D H 0 process is endothermic E H 0 since cold packs are sealed Ans C Difficulty E A 670 J B 1300 J C 27 kJ D 54 kJ E 100 kJ Ans D Difficulty M 5 A common laboratory reaction is the neutralization of an acid with a base When 50 0 mL of 0 500 M HCl at 25 0 C is added to 50 0 mL of 0 500 M NaOH at 25 0 C in a coffee cup calorimeter the temperature of the mixture rises to 28 2 C What is the heat of reaction per mole of acid Assume the mixture has a specific heat capacity of 4 18 J g K and that the densities of the reactant solutions are both 1 00 g mL 6 Calculate q when 28 6 g of water is heated from 22 0 C to 78 3 C A 0 385 kJ B 1 61 kJ C 6 74 kJ D 9 37 kJ E 1 61 103 kJ 7 Calculate the H rxn for the following reaction H f SiO2 s 910 9 kJ mol H f SiCl4 g 657 0 kJ mol H f HCl g 92 3 kJ mol H f H2O g 241 8 kJ mol SiO2 s 4HCl g SiCl4 g 2H2O g A 139 5 kJ B 137 4 kJ C 104 4 kJ D 104 4 kJ E 139 5 kJ 8 Balance the following redox equation using the smallest integers possible and select the correct coefficient for the hydrogen sulfite ion HSO3 MnO4 A 1 B 2 C 3 D 5 E 10 aq H aq Mn2 aq SO4 Ans D Difficulty M Ans E Difficulty E 2 aq H2O l aq HSO3 9 A Snickers candy bar contains 280 Calories of which the fat content accounts for 120 Calories What is the energy of the fat content in kJ 5 0 10 1 kJ 29 kJ 5 0 102 kJ A B C Ans C Difficulty E D E 1 2 103 kJ 5 0 105 kJ 10 The FM station KDUL broadcasts music at 99 1 MHz Find the wavelength of these waves A 1 88 10 2 m B 0 330 m C 3 03 m D 5 33 102 m E 103 m Ans C Difficulty M 11 Atomic orbitals developed using quantum mechanics describe regions of space in which one is most likely to find an electron describe exact paths for electron motion give a description of the atomic structure which is essentially the same as the Bohr allow scientists to calculate an exact volume for the hydrogen atom are in conflict with the Heisenberg Uncertainty Principle A B C model D E Ans A Difficulty M 12 Line spectra from all regions of the electromagnetic spectrum including the Paschen series of infrared lines for hydrogen are used by astronomers to identify elements present in the atmospheres of stars Calculate the wavelength of the photon emitted when the hydrogen atom undergoes a transition from n 5 to n 3 R 1 096776 107 m 1 A 205 1 nm B 384 6 nm C 683 8 nm D 1282 nm E 1500 nm Ans D Difficulty M 13 In the quantum mechanical treatment of the hydrogen atom which one of the following combinations of quantum numbers is not allowed Ans E Difficulty E 14 What type of spectrum if any would be produced if the light radiated by a heated atomic gas were to be dispersed through a prism a continuous band of color a continuous band of color with some dark lines missing wavelengths only blue light only red light discrete lines of different colors A B C D E Ans E Difficulty M 15 A piece of copper metal is initially at 100 0 C It is dropped into a coffee cup calorimeter containing 50 0 g of water at a temperature of 20 0 C After stirring the final temperature of both copper and water is 25 0 C Assuming no heat losses and that the specific heat capacity of water is 4 18 J g K what is the heat capacity of the copper in J K A 2 79 J K B 3 33 J K C 13 9 J K D 209 J K E none of the above Ans C Difficulty M 16 Which one of the following equations represents the formation reaction of CH3OH l A C g 2H2 g O2 g CH3OH l B C g 4H g O g CH3OH l C C graphite 4H g O g CH3OH l D C diamond 4H g O g CH3OH l E C graphite 2H2 g O2 g CH3OH l Ans E Difficulty E 17 The highly exothermic thermite reaction in which aluminum reduces iron III oxide to elemental iron has been used by railroad repair crews to weld rails together 2Al s Fe2O3 s 2Fe s Al2O3 s H 850 kJ What mass of iron is formed when 725 kJ of heat are released A 47 g B 65 g C 95 g D 112 g E 130 g Ans C Difficulty M 1212 Given the following data 18 2O3 g 3O2 g O2 g 2O g NO g O3 g NO2 g O2 g calculate H for the reaction NO g O …