Exam04answersvr302

Exam04answersvr302 - Cheung, Anthony Exam 4 Due: Dec 6...

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Cheung, Anthony – Exam 4 – Due: Dec 6 2006, 1:00 pm – Inst: McCord 1 This print-out should have 20 questions. Multiple-choice questions may continue on the next column or page – fnd all choices beFore answering. The due time is Central time. C 6 H 5 COOH = 122.1 g/mol (benzoic acid) C 3 H 8 = 44.1 g/mol (propane) ozone is O 3 001 (part 1 oF 1) 10 points Which one oF the Following thermodynamic quantities is NOT a state Function? 1. heat correct 2. temperature 3. pressure 4. entropy 5. Free energy Explanation: All except heat are independent oF path and are dependent solely on the current state oF the system. Heat (as well as work) is not a state Function. It is dependent on the process or pathway. HOW you got there DOES a±ect the value oF heat and work. 002 (part 1 oF 1) 8 points The process oF water Freezing to Form ice at 0 C is 1. an endothermic chemical reaction. 2. an endothermic phase change. 3. an exothermic chemical reaction. 4. an exothermic phase change. correct 5. neither exothermic nor endothermic. Explanation: Heat must be removed From the water For it to Freeze. This is exothermic. 003 (part 1 oF 1) 12 points The temperature oF 2.00 mol CO 2 (g) is in- creased From 10 C to 150 C at constant pres- sure. Calculate the change in the entropy oF carbon dioxide. Assume ideal behavior. 1. +23 . 30 J/K correct 2. +17 . 71 J/K 3. +11 . 70 J/K 4. - 11 . 70 J/K 5. - 23 . 30 J/K Explanation: T 1 = 10 C = 283 K T 2 = 150 C = 423 K n = 2 mol C p , m = 8 . 314 J mol · K Δ S = n C p , m ln µ T 2 T 1 = (2 mol) 7 2 ( 8 . 314 J mol · K ) × ln µ 423 K 283 K = 23 . 3912 J / K 004 (part 1 oF 1) 12 points Trapped on a desert island with a desper- ate need to know the boiling point oF chlo- roForm (CHCl 3 ), you come across some old thermodynamic tables that include the Fol- lowing data: ²or CHCl 3 ( ): Δ H 0 f = - 134 . 5 kJ / mol , S 0 = 202 J / mol · K ²or CHCl 3 (g): Δ H 0 f = - 103 . 1 kJ / mol , S 0 = 295 . 6 J / mol · K Using the data, what is the approximate boiling point oF chloroForm? 1. 349 K 2. 273 K 3. 335 K correct
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Cheung, Anthony – Exam 4 – Due: Dec 6 2006, 1:00 pm – Inst: McCord 2 4. 665 K Explanation: Δ H 0 f , CHCl 3 ( ) = - 134 . 5 kJ / mol S 0 CH 3 Cl 3 ( ) = 202 J / mol · K Δ H 0 f , CHCl 3 (g) = - 103 . 1 kJ / mol S 0 CHCl 3 (g) = 295 . 6 J / mol · K Δ H vap = X n Δ H f , prod - X n Δ H f , rct = ( - 103 . 1 kJ / mol) - ( - 134 . 5 kJ / mol) = 31 . 4 kJ / mol Δ S vap = X n Δ S f , prod - X n Δ S f , rct
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This note was uploaded on 11/11/2010 for the course CH 301 taught by Professor Fakhreddine/lyon during the Fall '07 term at University of Texas.

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Exam04answersvr302 - Cheung, Anthony Exam 4 Due: Dec 6...

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