ch302 - Mitchell, Viviane – Homework 1 – Due: Sep 11...

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Unformatted text preview: Mitchell, Viviane – Homework 1 – Due: Sep 11 2007, 11:00 am – Inst: James Holcombe 1 This print-out should have 31 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. The due time is Central time. 001 (part 1 of 1) 10 points The vapor pressure of CH 3 COCH 3 (propa- none or acetone), is 67 Torr at 0 ◦ C and 222 Torr at 25 ◦ C. What is the normal boiling point of propanone? The universal gas con- stant is 8 . 314 J K · mol . Correct answer: 55 . 941 ◦ C. Explanation: T 1 = 0 ◦ C + 273 . 15 = 273 . 15 K T 2 = 25 ◦ C + 273 . 15 = 298 . 15 K P 1 = 67 Torr P 2 = 222 Torr P = 1 atm = 760 Torr R = 8 . 314 J K · mol Using the Clausius-Clapeyron equation, ln µ P 1 P 2 ¶ = Δ H ◦ vap R µ 1 T 2- 1 T 1 ¶ R ln µ P 1 P 2 ¶ 1 T 2- 1 T 1 = Δ H ◦ vap Δ H ◦ vap = ( 8 . 314 J K · mol ) ln µ 67 Torr 222 Torr ¶ 1 298 . 15 K- 1 273 . 15 K = 32445 . 7 J / mol . Applying the Clausius-Clapeyron equation again, ln µ P P 2 ¶ = Δ H ◦ vap R µ 1 T 2- 1 T ¶ R Δ H ◦ vap ln µ P P 2 ¶ = 1 T 2- 1 T 1 T = 1 T 2- R Δ H ◦ vap ln µ P P 2 ¶ = 1 298 . 15 K- 8 . 314 J K · mol 32445 . 7 J / mol ln µ 760 Torr 222 Torr ¶ = 0 . 00303867 ◦ C T = 1 . 00303867 ◦ C = 329 . 091 ◦ C- 273 . 15 = 55 . 941 K 002 (part 1 of 1) 10 points Arsine (AsH 3 ) is a highly toxic compound used in the electronic industry for the pro- duction of semiconductor. Its vapor pressure is 35 Torr at- 111 . 95 ◦ C and 253 Torr at- 83 . 6 ◦ C. What is the standard enthalpy of vaporization of arsine? Correct answer: 17 . 7248 kJ / mol. Explanation: T 1 =- 111 . 95 ◦ C + 273 . 15 = 161 . 2 K P 1 = 35 Torr P 2 = 253 Torr T 2 =- 83 . 6 ◦ C + 273 . 15 = 189 . 55 K P = 1 atm = 760 Torr Using the Clausius-Clapeyron equation, ln µ P 1 P 2 ¶ = Δ H ◦ vap R µ 1 T 2- 1 T 1 ¶ R ln µ P 1 P 2 ¶ 1 T 2- 1 T 1 = Δ H ◦ vap Δ H ◦ vap = ( 8 . 314 J K · mol ) ln µ 35 Torr 253 Torr ¶ 1 189 . 55 K- 1 161 . 2 K = 17724 . 8 J / mol = 17 . 7248 kJ / mol . 003 (part 1 of 1) 10 points The vapor pressure of CH 3 COCH 3 (propa- none or acetone), is 67 Torr at 0 ◦ C and 222 Torr at 25 ◦ C. What is the standard entropy of vaporization of propanone? Correct answer: 0 . 0985919 J K · mol . Explanation: T 1 = 0 ◦ C + 273 . 15 = 273 . 15 K Mitchell, Viviane – Homework 1 – Due: Sep 11 2007, 11:00 am – Inst: James Holcombe 2 P 1 = 67 Torr P 2 = 222 Torr T 2 = 25 ◦ C + 273 . 15 = 298 . 15 K P = 1 atm = 760 Torr Using the Clausius-Clapeyron equation, ln µ P 1 P 2 ¶ = Δ H ◦ vap R µ 1 T 2- 1 T 1 ¶ R ln µ P 1 P 2 ¶ 1 T 2- 1 T 1 = Δ H ◦ vap Δ H ◦ vap = ( 8 . 314 J K · mol ) ln µ 67 Torr 222 Torr ¶ 1 298 . 15 K- 1 273 . 15 K = 32445 . 7 J / mol ....
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This note was uploaded on 06/16/2008 for the course CH 302 taught by Professor Holcombe during the Fall '07 term at University of Texas.

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ch302 - Mitchell, Viviane – Homework 1 – Due: Sep 11...

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