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Unformatted text preview: Gauthier, Joseph Exam 4 Due: Dec 6 2007, 11:00 pm Inst: Vandenbout 1 This print-out should have 26 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. The due time is Central time. Vanden Bout ONLY ! ! ! ! 001 (part 1 of 1) 10 points 1.95 mol of an ideal gas at 300 K and 3.00 atm expands from 16 L to 28 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 28 L. Which of the following is CORRECT? 1. w =- 4 . 57 kJ for (1) and w =- 1 . 46 kJ for (2) 2. w = 0 for (1) and w =- 1 . 46 kJ for (2) correct 3. w = 0 for the overall process 4. w =- 4 . 57 kJ for the overall process 5. w =- 6 . 03 kJ for the overall process Explanation: step 1: volume is constant and w = 0 step 2: w =- P V =- 1 . 2(12) =- 14 . 4 L atm-14.4 L atm x 101.325 J/L atm = -1459 J =-1.46 kJ 002 (part 1 of 1) 10 points How much heat is required to heat 24 g of solid silver from 85 C to liquid silver at 961 C? The specific heat of solid silver is 0 . 235 J / g C, and the heat of fusion of silver at its melting point of 961 C is 11.3 kJ/g. Correct answer: 276 . 141 kJ. Explanation: Must heat silver to the melting point and then melt it. mass( C p )( T ) + H fus mass = q (heat) 003 (part 1 of 1) 10 points The formation of solid calcium chloride from a gas of its ions is an endothermic process. 1. True 2. False correct Explanation: 004 (part 1 of 1) 10 points The value of H for which of the following reactions is referred to as the standard molar enthalpy of formation of carbon monoxide? 1. C(g) + 1 2 O 2 (g) CO(g) 2. C(graphite) + O(g) CO(g) 3. C(g) + O(g) CO(g) 4. C(graphite) + 1 2 O 2 (g) CO(g) correct Explanation: The formation reaction for any compound is a chemical reaction where only elements in their standard states are used as reactants and exactly ONE mole of the compound is formed as the product. ALL elements in their standard states are assigned H f values of zero. 005 (part 1 of 1) 10 points The First Law of Thermodynamics deals with 1. destruction of energy. 2. conservation of energy. correct 3. creation of energy. 4. conservation of mass. Explanation: The First Law of Thermodynamics states that the total amount of energy in the uni- verse is constant. Energy is conserved; it Gauthier, Joseph Exam 4 Due: Dec 6 2007, 11:00 pm Inst: Vandenbout 2 cannot be created nor destroyed. 006 (part 1 of 1) 10 points The sublimation of solid carbon dioxide is a spontaneous process. Predict the sign (+,- , or 0) of G r , H r , and S r , respectively....
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