# HW9_Answer - Chem340 Homework 9 P8.3 An ideal solution is...

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Chem340 Homework 9 P8.3) An ideal solution is formed by mixing liquids A and B at 298 K. The vapor pressure of pure A is 180. Torr and that of pure B is 82.1 Torr. If the mole fraction of A in the vapor is 0.450, what is the mole fraction of A in the solution? The mol fraction of A in the ideal solution of liquids A and B is given by:  0.272 0.450 Torr 180 Torr 82.1 Torr 180 Torr 82.1 0.450 y p p p p y x A A B A B A A P8.4) A and B form an ideal solution. At a total pressure of 0.900 bar, y A = 0.450 and x A = 0.650. Using this information, calculate the vapor pressure of pure A and of pure B. * * * ** * * * * * * 0.900 bar 0.450 0.623 bar 0.650 0.450 0.650 0.450 0.650 1 0.450 2.27 0.450 1 0.650 1.414 bar total A a B total total B total a A AB A aB A A B A B A B Px P y P Py P P x yP x PP P y P P P P P     P8.5) A and B form an ideal solution at 298 K, with x A = 0.600, P A * 105 Torr, and P B * 63.5 Torr. a. Calculate the partial pressures of A and B in the gas phase. b. A portion of the gas phase is removed and condensed in a separate container. Calculate the partial pressures of A and B in equilibrium with this liquid sample at

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298 K. a) Calculate the partial pressures of A and B in the gas phase.  * * 0.600 105 Torr = 63.0 Torr 1 0.400 63.5 Torr = 25.4 Torr AA A BA B Px P P   b) A portion of the gas phase is removed and condensed in a separate container. Calculate the partial pressures of A and B in equilibrium with this liquid sample at 298 K. The composition of the initial gas is given by 63.0 Torr 0.713; 0.287 88.4 Torr A AB P yy PP  * * For the portion removed, the new and values are the previous and values. 0.713 105 Torr = 74.9 Torr 1 0.287 63.5 Torr = 18.2 Torr A B xx P P P8.7) Assume that 1-bromobutane and 1-chlorobutane form an ideal solution. At 273 K, P chloro * 3790 Pa and P bromo * 1394 Pa. When only a trace of liquid is present at 273 K, y chloro = 0.75. a. Calculate the total pressure above the solution. b. Calculate the mole fraction of 1-chlorobutane in the solution. c. What value would Z chloro have in order for there to be 4.86 mol of liquid and 3.21 mol of gas at a total pressure equal to that in part (a)? [ Note : This composition is different from that of part (a).] a) Calculate the total pressure above the solution.
 ** * total 3790 Pa P 3790 Pa 1394 Pa 0.75 3790 Pa 1394 Pa 3790 Pa 1394 Pa 2651 Pa 3790 Pa 0.75 3790 Pa 1394 Pa chloro total chloro bromo chloro total chloro bromo total total PP y P P P    b) Calculate the mole fraction of 1-chlorobutane in the solution. * 1 2651 Pa 1394 Pa 0.525 3790 Pa 1394 Pa total chloro chloro chloro bromo total bromo chloro chloro bromo Px P xP x   c) What value would Z chloro have in order that there are 4.86 moles of liquid and 3.21 moles of gas at a total pressure equal to that in part a)? (This composition is different than that in part a.) * * * 3790 Pa 2651 Pa 3790 Pa 1394 Pa 0.750 2651 Pa 3790 Pa 1394 Pa 0.750 13 chloro total chloro bromo chloro total chloro bromo chloro bromo chloro chloro bromo chloro chloro y P yP x P y   94 Pa 0.525 3790 Pa + 1394 Pa 3790 Pa 0.750 3.21 mol 0.750 + 4.86 mol 0.525 0.61 3.21 mol + 4.86 mol tot tot liq

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## This note was uploaded on 08/23/2011 for the course CHEM 342 taught by Professor Prestonsnee during the Spring '08 term at Ill. Chicago.

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HW9_Answer - Chem340 Homework 9 P8.3 An ideal solution is...

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