# hw7 - Killough Ian – Homework 7 – Due Nov 7 2006 11:00...

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Unformatted text preview: Killough, Ian – Homework 7 – Due: Nov 7 2006, 11:00 pm – Inst: Donna C Lyon 1 This print-out should have 20 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. The due time is Central time. This HW assignment is due Tuesday, November 7, by 11PM. 001 (part 1 of 1) 10 points Calculate the mass of CO 2 produced by the combustion of a tank of gasoline. Assume the mass of a tank of gasoline is 46.0 kg and that gasoline is pure octane (C 8 H 18 ). (1 lb = 454 g) 1. 420 lb 2. None of these 3. 142 lb 4. 278 lb 5. 114 lb 6. 312 lb correct 7. 368 lb 8. 195 lb Explanation: The balanced equation is 2C 8 H 18 + 2SO 2 → 6CO 2 + 18H 2 O MW C 8 H 18 = 8(12 . 011 g / mol) + 18(1 . 0079 g / mol) = 114 . 23 g / mol MW CO 2 = 12 . 011 g / mol + 2(15 . 999 kg / mol) = 44 . 01 g / mol (46 . 0 kg C 8 H 18 ) × 1000 g 1 kg × 1 mol C 8 H 18 114 . 23 g C 8 H 18 × 16 mol CO 2 2 mol C 8 H 18 × 44 . 01 g CO 2 1 mol CO 2 × 1 lb 454 g = 312 . 294 lb Alternate Solution ; The wt% of C in CO 2 is 12 . 011 g / mol 12 . 011 g / mol + 2(15 . 9944 g / mol) × 100% = 27 . 2979% , so 100 g of CO 2 contains 27.29 g of C. The wt% of C in C 8 H 18 is 8(12 . 011 g / mol) 8(12 . 011 g / mol) + 18(1 . 0079 g / mol) × 100% = 84 . 12% , so 100 g of C 8 H 1 8 contains 84.12 g of C. (46 . 0 kg C 8 H 18 ) × 1000 g 1 kg × 84 . 12 g C 100 g C 8 H 18 × 100 g CO 2 27 . 29 g C × 1 lb 454 g = 312 lb C 002 (part 1 of 1) 10 points One process by which nickel is recovered from nickel(II) sulfide ores is to heat the ore in air. During this “roasting” process, molecular oxygen reacts with the nickel(II) sulfide to produce nickel(II) oxide and sulfur dioxide gas. What is the coefficient of sulfur dioxide in the balanced chemical equation for the reac- tion? (Balance the equation with the smallest possible whole number coefficients.) 1. 1 2. 11 3. 3 4. 7 5. 12 Killough, Ian – Homework 7 – Due: Nov 7 2006, 11:00 pm – Inst: Donna C Lyon 2 6. 9 7. 8 8. 10 9. 2 correct 10. 6 Explanation: The balanced equation for the reaction is 2NiS(s) + 3O 2 (g) → 2NiO(s) + 2SO 2 (g) 003 (part 1 of 1) 10 points Hot coffee in a vacuum flask (thermos) is an example of what type of system? 1. isolated correct 2. closed 3. open Explanation: 004 (part 1 of 1) 10 points 2.00 mol of an ideal gas at 300 K and 3.00 atm expands from 6.00 L to 18.00 L and a final pressure of 1.20 atm in two steps: (1) the gas is cooled at constant volume until its pressure has fallen to 1.20 atm, and (2) it is heated and allowed to expand against a constant pressure of 1.20 atm un- til its volume reaches 18.00 L. Which of the following is CORRECT? 1. w =- 4 . 57 kJ for the overall process 2. w =- 6 . 03 kJ for the overall process 3. w = 0 for the overall process 4. w = 0 for (1) and w =- 1 . 46 kJ for (2) correct 5. w =- 4 . 57 kJ for (1) and w =- 1 . 46 kJ for (2) Explanation: 005 (part 1 of 1) 10 points A CD player and its battery together do 500 kJ of work, and the battery also releases 250...
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hw7 - Killough Ian – Homework 7 – Due Nov 7 2006 11:00...

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