Thermo ch 9 10 - Martin, Robert Homework 2 Due: Jan 25...

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Unformatted text preview: Martin, Robert Homework 2 Due: Jan 25 2007, 5:00 pm Inst: Deb Walker 1 This print-out should have 29 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. The due time is Central time. Thermo Review 001 (part 1 of 1) 2 points Calculate the heat of formation of butane (C 4 H 10 ) using the following balanced chemi- cal equation and information. Write out the solution according to Hesss law. C(s) + O 2 (g)- CO 2 (g) H f =- 393 . 8 kJ / mol H 2 (g) + 1 2 O 2 (g)- H 2 O( ) H f =- 282 . 7 kJ / mol 4 CO 2 (g) + 5 H 2 O- C 4 H 10 (g) + 13 2 O 2 (g) H c = 2877 . 6 kJ / mol Answer in units of kJ. 002 (part 1 of 1) 2 points Would more heat be released when 1.00 gram of CH 4 (g) is burned in excess O 2 (g) to form CO 2 (g) and H 2 O( ) in a constant-pressure calorimeter or in a constant-volume calorime- ter? 1. It would be the same either way. 2. It could be either one, depending on the pressure. 3. More heat would be released in a constant volume calorimeter. 4. More heat would be released in a constant pressure calorimeter. 003 (part 1 of 1) 2 points A 1.00 g sample of n-hexane (C 6 H 14 ) under- goes complete combustion with excess O 2 in a bomb calorimeter. The temperature of the 1502 g of water surrounding the bomb rises from 22.64 C to 29.30 C. The heat capacity of the calorimeter is 4042 J/ C. What is U for the combustion of n-C 6 H 14 ? One mole of n-C 6 H 14 is 86.1 g. The specific heat of water is 4.184 J / g C. 1.- 7 . 40 10 4 kJ/mol 2.- 5 . 92 10 3 kJ/mol 3.- 1 . 15 10 4 kJ/mol 4.- 4 . 52 10 3 kJ/mol 5.- 9 . 96 10 3 kJ/mol 004 (part 1 of 1) 2 points The combustion of sucrose (a carbohydrate) is shown as follows C 12 H 22 O 11 (s) + 12 O 2 (g) 12 CO 2 (g) + 11 H 2 O( ) Calculate the work, H at 298 K, and E for the combustion of one mole of sucrose at 25 C and pressure. H f sucrose =- 2218 kJ/mol. 1. w = 5648 kJ, H = 0 kJ, and E =- 5648 kJ 2. w = 0 kJ, H = +5648 kJ, and E = +5648 kJ 3. w = 0 kJ, H = 0 kJ, and E = 0 kJ 4. w = 0 kJ, H =- 5648 kJ, and E =- 5648 kJ 005 (part 1 of 1) 2 points The standard molar internal energy of forma- tion of N 2 O 5 (g) is 17.433 kJ/mol at 298 K. What is the standard molar enthalpy of for- mation of N 2 O 5 (g) at the same temperature? 1. 11.24 kJ/mol 2. 19.07 kJ/mol 3. 7.921 kJ/mol 4. 4.955 kJ/mol Martin, Robert Homework 2 Due: Jan 25 2007, 5:00 pm Inst: Deb Walker 2 5. None of the other answers is correct within 2%. 006 (part 1 of 1) 2 points Given the absolute entropies (in J/mol K) NO 2 = 240 H 2 O = 69.91 HNO 3 = 146 J/mol K NO = 210.7 at 298 K and 1 atm, evaluate S for the reaction 3 NO 2 (g) + H 2 O( ) 2 HNO 3 (aq) + NO(g) 1. S = +257 J / mol K at 25 C 2. S =- 287 J / mol K at 25 C 3. S = +144 J / mol K at 25 C 4. S = +1009 J / mol K at 25 C 5. S =- 770 J / mol K at 25...
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Thermo ch 9 10 - Martin, Robert Homework 2 Due: Jan 25...

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