solutionEXAM 1_pdf - Version 096 Exam 1 Fakhreddine(52395 This print-out should have 25 questions Multiple-choice questions may continue on the next

solutionEXAM 1_pdf - Version 096 Exam 1 Fakhreddine(52395...

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Version 096 – Exam 1 – Fakhreddine – (52395) 1 This print-out should have 25 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 001 12.0 points specific heat of H2O(l) = 4.18 J/g.C, enthalpy of evaporation of water = 2.26 x 103 J/g; spe- cific heat of H2O (g) = 2.03 J/g.C; enthalpy of fusion of ice = 334.0 J/g; and specific heat of H2O(s) = 2.09 J/g.C Consider an insulated system containing 150 g of liquid water and 150 g of ice at equilibrium under atmospheric pressure. A total of 17 g of steam at 110 C is admitted to the system. What is the phase composition and temperature when equilibrium is reestab- lished? 1. 300 g of water and 17 g of ice at 0 C 2. 317 g of water at 3.2 C 3. 317 g of water at 6.8 C 4. 304 g of water and 13 g of ice at 0 C correct 5.310 g of water and 7 g of ice at 0C6.317 g of water at 15.3C1.None of these is correct.2.strong binding in the solid and weaksolvent-solute interaction. Explanation: 002 12.0 points How many grams of methanol (CH 3 OH) are needed to lower the freezing point of 400 mL of water by 2.5 C? ( K f water = 1 . 86 C/molality) 1. 9.71 2. 17.2 correct 3. 12.8 4. 21.8 5. 18.3 Explanation: K f H 2 O = 1 . 86 C /m V water = 400 L FP depression = 2.5 C Δ T f = K f · m m = Δ T f K f = 2 . 5 C 1 . 86 C /m = 1 . 344 m m H 2 O = 400 mL × 1 . 00 g mL × 10 3 kg g = 0 . 4 kg H 2 O m = n CH 3 OH kg water = g CH 3 OH MW CH 3 OH kg water g CH 3 OH = m (kg water) (MW CH 3 OH ) = parenleftbigg 1 . 344 mol CH 3 OH kg water parenrightbigg × (0 . 400 kg water) × parenleftbigg 32 . 0 g CH 3 OH mol CH 3 OH parenrightbigg = 17 . 2 g CH 3 OH 003 5.0 points Dissociation of a solid is aided by 3. strong interaction between solvent molecules. 4. weak binding of species in the solid and strong interactions between the solvent and solute. correct Explanation: Weak intermolecular forces in the solute facilitate separation of its particles and strong attractive forces between solute and solvent facilitate dissociation of a solid. 004 12.0 points Methanol (CH 3 OH) and ethanol (C 2 H 5 OH) are common organic solvents. The vapor pressures of pure methanol and pure ethanol
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Version 096 – Exam 1 – Fakhreddine – (52395) 2at 25C are 122.7 torr and 58.9 torr, respec-tively. If the mole fraction of CH3OH in themixture of the two solvents at 25C is 0.2,what is the mole fraction of C2H5OH in thevapor phase that is in equilibrium with theliquid mixture?
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