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# Mary_review_ques_-_to_post - ChE102 Fall 2011 Final Exam...

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ChE102 Fall 2011 - Final Exam Review Questions 1- At a temperature of 0 ° C, the concentration of N 2 dissolved in water is 1.05 × 10 -3 mol/L under a N 2 pressure of 1.00 atm. Air is added to the system, raising the total pressure to 6.0 atm, while the temperature is kept constant at 0 o C. Calculate the concentration of the N 2 in the water under this new pressure. Data : Air is taken to be 21 mol % O and 79 mol % N A) 5.2 × 10 -3 mol/L B) 2.8 × 10 -3 mol/L C) 4.6 × 10 -3 mol/L D) 1.5 × 10 -3 mol/L E) 1.5 × 10 -2 mol/L 2- A solution composed of 39 g of benzene (C 6 H 6 ) and 138 g of toluene (C 7 H 8 ) at 25ºC is placed in an evacuated vessel and liquid; vapour equilibrium is achieved. At 25ºC the vapour pressure of C 6 H 6 is 95.1 torr and of toluene is 28.4 torr. What is the mole fraction of benzene in the vapour phase when equilibrium is achieved? A) 0.25 B) 0.53 C) 0.78 D) 0.86 E) 0.95 3- Consider the following statements about the phase diagram for carbon dioxide (CO 2 ), shown in the figure below. i) The normal boiling point temperature of CO 2 is approximately -78ºC. ii) The critical point is the temperature and pressure at which the liquid, solid, and gaseous phases co-exist. iii) A sample of carbon dioxide at 100 atm is subjected to increasing temperatures from -80ºC to 0ºC. This sample starts as a solid and melts to liquid carbon dioxide. iv) At atmospheric pressure and temperatures approaching absolute zero, CO 2 exists only as a solid. v) At temperatures above 31ºC and pressures above 73 atm, CO 2 is present as a gas.

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ChE102 Fall 2011 - Final Exam Review Questions The number of true statements is: A) 1 B) 2 C) 3 D) 4 E) 5
ChE102 Fall 2011 - Final Exam Review Questions 4- A solution of 36.0 g of an unknown solute in 1.20 kg of water is found to have a freezing point of -0.93°C. The solute is known not to dissociate and to have an empirical

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Mary_review_ques_-_to_post - ChE102 Fall 2011 Final Exam...

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