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# finalexamsolns - Hou Taylor Final 1 Due 2:00 am Inst...

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Hou, Taylor – Final 1 – Due: Dec 10 2007, 2:00 am – Inst: Brodbelt 1 This print-out should have 40 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. The due time is Central time. Brodbelt CH301 Final Exam Fall 2007 Use of programmable calculators or cell phones or IPODS is considered cheating and is prohibited. You may not leave the room for any reason. You may not start the exam after 2:15 pm. GOOD LUCK! 001 (part 1 of 1) 10 points What mass of CH 4 is required to produce 14.5 g of H 2 O if the reaction has a 73.5% yield? CH 4 + 2 O 2 CO 2 + 2 H 2 O 1. 35.0 g 2. 6.46 g 3. 2.19 g 4. 4.73 g 5. 0.548 g 6. 18.9 g 7. 8.75 g correct Explanation: yield = 14 . 5 g % yield = 65% 14.5 g is the actual yield. We need to calculate the theoretical yield: 65 . 0 100 = 14 . 5 g CO 2 th . yield th . yield = 22 . 3 g CO 2 ? g O 2 = 22 . 3 g CO 2 × 1 mol CO 2 44 g CO 2 × 2 mol O 2 1 mol CO 2 × 32 g O 2 1 mol O 2 = 32 . 4 g O 2 002 (part 1 of 1) 10 points Consider the compound peroxyacetylni- trate, an eye irritant in smog. O N C O O O O CH 3 Predict the indicated bond angle. 1. 60 2. 109.5 3. 120 correct 4. 30 5. 90 Explanation: There are 46 valence electrons; the struc- ture does not show lone pairs on the O atoms or the C - H bonds. There will be three lone pairs on the terminal O singly bonded to N, and two lone pairs on all other O atoms. 003 (part 1 of 1) 10 points SO 3 has how many regions of high electron density and how many bonded electrons when the octet rule is strictly obeyed? 1. 4; 5 2. 4; 6 3. 3; 6 4. 4; 8 5. 3; 10 6. 4; 14 7. 5; 14 8. 3; 8 correct

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Hou, Taylor – Final 1 – Due: Dec 10 2007, 2:00 am – Inst: Brodbelt 2 9. 5; 6 Explanation: One of the three resonant structures is S O O O 004 (part 1 of 1) 10 points Why is the heat of vaporization of water much larger than the heat of melting (fusion)? 1. Liquid water molecules are held close to- gether by hydrogen bonds, but solid water molecules (ice) are held close together by co- valent bonds. 2. The bonds holding liquid molecules to- gether are stronger than those holding to- gether solid water molecules (ice). 3. The statement is not true; the heat of melting is actually greater than the heat of vaporization. 4. Melting only requires a partial disruption of the hydrogen bonding network of water whereas vaporization requires complete disso- ciation of the hydrogen bonds. correct 5. Vaporization is a very exothermic process while melting is endothermic. Explanation: 005 (part 1 of 1) 10 points A 750.0 mL metal bulb is filled with 42.1 g of CH 4 and 3.23 g of NH 3 . If the amount of pressure contributed by CH 4 is 111.2 atm, then what is pressure due to NH 3 ? 1. 8.53 atm 2. 73.8 atm 3. 2.39 atm 4. 0.477 atm 5. 8.05 atm correct 6. 1.81 atm Explanation: n CH 4 = 42 . 1 g · mol 16 g = 2 . 63 mol n NH 3 = 3 . 23 g · mol 17 g = 0 . 19 mol n total = 2 . 82 mol V = 75 mL = 0 . 075 L T = 315 C + 273 = 588 K Applying the ideal gas law equation, P V = n R T P = n R T V P = (2 . 82 mol) ( 0 . 08206 L · atm mol · K ) (588 K) 0 . 075 L · 760 torr 1 atm = 1 . 37883 × 10 6 torr 006 (part 1 of 1) 10 points Consider this reaction of methanol with oxy- gen: 2 CH 3 OH( ) + 3 O 2 (g) -→ 2 CO 2 (g) + 4 H 2 O(g) If 0.35 moles of methanol react with excess oxygen to release 200.5 kJ of energy as heat,
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finalexamsolns - Hou Taylor Final 1 Due 2:00 am Inst...

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