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sample exam 4 solutions

# sample exam 4 solutions - mao(tm23477 Sample Exam Four...

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mao (tm23477) – Sample Exam Four – Shear – (52375) 1 This print-out should have 27 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. DrRuth says: In all cases, select the answer that BEST answers the question asked. Read the whole thing first and plan which to answer first because you feel confident about them. Notice the harder ones and save them up till last so you don’t use up all your time working on them. Shear 52375 1 L atm = 101.325 J 1 cal = 4.184 J R = see back of answer sheet 001 10.0 points An isolated system can only exchange energy with the surroundings. 1. True 2. False correct Explanation: An isolated system cannot exchange energy nor matter with the surroundings. 002 10.0 points Which one of the following thermodynamic quantities is NOT a state function? 1. work correct 2. enthalpy 3. entropy 4. internal energy 5. free energy Explanation: Internal energy ( E ), free energy ( G ), en- thalpy ( H ) and entropy ( S ) are state func- tions. They are independent of path and are dependent solely on the initial and final states. Work is not a state function. It is dependent on the process or pathway. 003 10.0 points Which of the following statements does NOT concern the First Law of Thermodynamics? 1. The energy of the universe is constant. 2. Energy cannot be created nor destroyed. 3. Spontaneous changes lead to more uni- versal disorder. correct 4. Energy can be transformed but never made from scratch. Explanation: The First Law of Thermodynamics states that the total amount of energy in the uni- verse is constant. Energy cannot be created nor destroyed, but it can be transferred and it can change form. The Second Law of Ther- modynamics addresses spontaneity. 004 10.0 points You have a 12 oz. can (355 mL) of beer. You test the temperature and see that it reads 0 C. Now this isn’t just any beer; this is Guinness and you’ve heard that Guinness is best at room temperature (20 C). If the specific heat of Guinness is 4.186 J / g · C, how much heat should you add in order to raise the tempera- ture? The density of Guinness is 1.2 g/mL. 1. 35.6 kJ correct 2. 33.6 J 3. 33.6 kJ 4. 83 J Explanation: 005 10.0 points Which of O 2 (g) , O 2 ( ) , H 2 (g) , H 2 ( ) , H 2 O(g) , H 2 O( ) have a heat of formation equal to zero?

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mao (tm23477) – Sample Exam Four – Shear – (52375) 2 1. All of them, but only at absolute zero 2. O 2 (g), H 2 (g) correct 3. O 2 (g), H 2 (g), H 2 O(g) 4. O 2 (g), O 2 ( ), H 2 (g), H 2 ( ), H 2 O(g), H 2 O( ) 5. O 2 (g), O 2 ( ), H 2 (g), H 2 ( ) Explanation: Molecules in their native state at STP have a heat of formation of zero. 006 10.0 points Which of the following reactions as written corresponds to a heat of formation reaction? 1. 2 H 2 (g) + O 2 (g) 2 H 2 O( ) 2. SO 2 (g) + 1 2 O 2 (g) SO 3 (g) 3. CO 2 (s) CO 2 (g) 4. Na(s) + 1 2 Cl 2 (g) NaCl(s) correct Explanation: All of the reactants in a formation reaction must be ELEMENTS in their thermochemical standard state. AND, to match table values, only 1 MOLE of product can be formed be- cause standard table values are in kJ/mol.
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sample exam 4 solutions - mao(tm23477 Sample Exam Four...

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