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Unformatted text preview: peeples (jjp2256) – HW01: Thermo and Collig Prop – walker – (51645) 1 This print-out should have 32 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 001 0.1 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 Hess’s law. C(s) + O 2 (g)-→ CO 2 (g) Δ H f =- 395 . 1 kJ / mol H 2 (g) + 1 2 O 2 (g)-→ H 2 O( ) Δ H f =- 285 . 4 kJ / mol 4 CO 2 (g) + 5 H 2 O-→ C 4 H 10 (g) + 13 2 O 2 (g) Δ H c = 2877 . 6 kJ / mol Answer in units of kJ. 002 0.1 points What mass of N 2 is formed when 18.1 g NH 3 is reacted with 90.4 g CuO? (The other products are copper metal and water.) 1. Cannot be determined unless limiting re- actant is known 2. 25.5 g 3. 10.6 g 4. 14.9 g 003 0.1 points A friend says that as a plant grows and takes an unordered set of molecules and puts them in a highly organized system the second law of thermodynamics is violated. Your best response is that 1. you must be thinking of the third law. 2. while the entropy involved in the plant growth decreased, the entropy in the universe increased as a result of this process. 3. the second law applies only to chemical systems and not biological systems. 4. the plant is not at equilibrium and hence the argument is invalid. 004 0.1 points A reaction for which Δ S and Δ H are negative can become spontaneous as the temperature 1. decreases. 2. remains the same. 3. increases. 005 0.1 points For a given reaction Δ G is very negative. Which of the following is FALSE? 1. Δ S for the reaction may be positive or negative. 2. The reaction should occur very rapidly because Δ G is very negative. 3. The entropy of the universe must increase as a result of this reaction occuring. 4. The reaction is termed spontaneous. 5. If Δ S is positive, then the reaction will probably be more spontaneous at higher tem- peratures. 006 0.1 points Which statement below is FALSE? 1. Endothermic reactions may be sponta- neous. 2. For reactions in which the reacting system becomes more disordered, Δ S is positive. 3. The entropy of a system increases when order increases. 4. For reactions that release heat to the surroundings, Δ H is negative. 5. If the free energy change of reaction is peeples (jjp2256) – HW01: Thermo and Collig Prop – walker – (51645) 2 negative the reaction will occur under the given conditions....
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This note was uploaded on 01/21/2011 for the course CH 302 taught by Professor Holcombe during the Spring '07 term at University of Texas at Austin.
- Spring '07