Chem 1202 Form 4 Fall 2024 Dr Gasery Exam 3 Chapters 5 and 19 Thermochemistry and Chemical Thermodynamics Instructions Use an 8 5 x 11 inch green and white scantron On Side Two of the scantron 1 Print your Last Name then First Name and bubble it in 2 Print and bubble in your complete correct LSU ID number 89 number 3 Bubble 4 in the Grade or Education box On Side One of the scantron 1 Print your name 2 Answers to the exam questions must go on side one Bubble the answers on 3 There is exactly one best answer for each question and you should NOT the scantron sheet using a pencil leave a question blank 4 On a numerical question choose the response closest to the correct answer This exam is closed notes and closed book You are not allowed to use your own scratch paper Only a scientific calculator is allowed during the exam NO graphing calculators Mark your answers in your Exam for future reference You can keep your Exam for further study Present your LSU ID and the front of your exam when submitting your scantron Useful Information and Constants The periodic table is located at the back of the exam R 8 314 0 08206 atm 101 3 J 1 L atm J mol K L mol Grxn o Hrxn o T Srxn o E q w S G Go RT ln Q Keq e Go RT q T q Cs m T q Ccal T wsys P V 1 1 A decrease in the entropy of the system is observed for which of the reactions below a 4 NH3 g 5 O2 g 4 NO g 6 H2O g b 2 HgO s 2 Hg l O2 g c UF6 s U s 3F2 g d K s 1 2 I2 g KI s e H2O s H2O g 2 Given the thermodynamic data in the table below calculate the equilibrium constant at 298 K for the reaction 2 SO2 g O2 g 2 SO3 g a 2 40 1024 b 1 06 c 1 95 d 3 82 x 1023 e More data is needed Use the table of thermodynamic data at 298 K below to answer questions 3 and 4 H f kJ mol S J K mol G f kJ mol Substance Calcium Ca CaCl2 Ca2 Chlorine Cl2 Cl O2 Oxygen H2O l Phosphorus P2 g PCl3 g POCl3 g Sulfur S s rhombic SO2 g SO3 g 0 0 0 0 795 8 226 7 167 2 285 83 144 3 288 1 542 2 269 9 395 2 41 4 104 6 200 8 222 96 56 5 205 0 69 91 218 1 311 7 325 31 88 248 5 256 2 0 0 0 0 748 1 209 2 131 2 237 13 218 1 311 7 502 5 300 4 370 4 2 3 What is the value of G at 25 C for the oxidation of solid elemental sulfur to gaseous sulfur trioxide according to the following reaction 2S s rhombic 3O2 g 2SO3 g 4 What is the value of S in J K for the oxidation of solid elemental sulfur to gaseous sulfur dioxide according to the reaction below S s rhombic O2 g SO2 g 5 Which of the following statements about the third law of thermodynamics is false a The third law describes the entropy of a pure crystalline substance at T 0K b At T 0K a pure crystalline solid has no translational vibrational or rotational c At T 0K a pure crystalline solid has zero possible microstates d A pure crystalline solid at T 0K has S 0 6 The standard free energy change at 298 K for the aqueous reaction A aq B aq C aq is G 3 0 kJ What is G at 298 K for this reaction when A 0 50 M B 0 50 M and C 2 0 M a 8 2 kJ mol b 3 0 kJ mol c 0 76 kJ mol d 0 43 kJ mol e 2 2 kJ mol 7 For which one of the following reactions is H rxn equal to the heat of formation of the product a N2 g 3H2 g 2NH3 g b 1 2 N2 g O2 g NO2 g c 6C s 6H g C6H6 l d P g 4H g Br g PH4Br l e 12C g 11H2 g 11O g C6H22O11 g a 740 8 b 370 4 c 370 4 d 740 8 e 185 2 a 485 4 b 248 5 c 11 6 d 248 5 e 11 6 motion 3 8 Which one of the following statements is true a Enthalpy is an intensive property b The enthalpy change for a reaction is independent of the state of the reactants and products c Enthalpy is a state function d H is the value of q measured under conditions of constant volume e The enthalpy change of a reaction is the reciprocal of the H of the reverse reaction 9 Which one of the following is an endothermic process a Ice melting b Water freezing c Boiling soup d Hydrochloric acid and barium hydroxide are mixed at 25 C the temperature increases e Both a and c 10 Which one of the following conditions would always result in an increase in the internal energy of the system a The system loses heat and does work on the surroundings b The system gains heat and does work on the surroundings c The system loses heat and has work done on it by the surroundings d The system gains heat and has work done on it by the surroundings e None of the above is correct 11 Which of the following statements is NOT a correct representation of the First Law of Thermodynamics a Entropy of an isolated system always increases b Energy lost by the system must be gained by its surroundings c The total amount of matter and energy in the universe is constant d In any process energy can be changed from one form to another but can neither be created nor destroyed e All statements are correct representations of the First Law of Thermodynamics 12 Which one of the following is always positive when a spontaneous process occurs 2nd law of thermodynamics a Ssystem b Ssurroundings c Suniverse d Huniverse e Hsurroundings 4 13 A 6 11 g sample of calcium carbonate CaCO3 s absorbs 84 J of heat upon which the temperature of the sample increases from 19 2 C to 35 9 C What is the specific heat of calcium carbonate a 0 82 J g K b 0 82 J g K c 31 J g K d 230 J g K e 8600 J g K 14 What is the enthalpy change in kJ of a chemical reaction that raises the temperature of 250 0 mL of solution having a density of 1 25 g mL by 3 33 C The specific heat of the solution is 3 74 J g K a 7 43 kJ b 12 …