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Version 096 – Exam 1 – Fakhreddine – (52395)1Thisprint-outshouldhave25questions.Multiple-choice questions may continue onthe next column or page – find all choicesbefore answering.00112.0 pointsspecific heat of H2O(l) = 4.18 J/g.C, enthalpyof evaporation of water = 2.26 x 103 J/g; spe-cific heat of H2O (g) = 2.03 J/g.C; enthalpyof fusion of ice = 334.0 J/g; and specific heatof H2O(s) = 2.09 J/g.CConsider an insulated system containing150 g of liquid water and 150 g of ice atequilibrium under atmospheric pressure.Atotal of 17 g of steam at 110◦C is admitted tothe system.What is the phase compositionand temperature when equilibrium is reestab-lished?1.300 g of water and 17 g of ice at 0◦C2.317 g of water at 3.2◦C3.317 g of water at 6.8◦C4.304 g of water and 13 g of ice at 0◦Ccorrect5.310 g of water and 7 g of ice at 0◦C6.317 g of water at 15.3◦C1.None of these is correct.2.strong binding in the solid and weaksolvent-solute interaction.Explanation:00212.0 pointsHowmanygramsofmethanol(CH3OH)are needed to lower the freezing point of400 mL of water by 2.5◦C? (Kfwater =1.86◦C/molality)1.9.712.17.2correct18.104.22.168.85.18.3Explanation:Kf H2O= 1.86◦C/mVwater= 400 LFP depression = 2.5◦CΔTf=Kf·mm=ΔTfKf=2.5◦C1.86◦C/m= 1.344mmH2O= 400 mL×1.00 gmL×10−3kgg= 0.4 kg H2Om=nCH3OHkg water=g CH3OHMWCH3OHkg waterg CH3OH =m(kg water) (MWCH3OH)=parenleftbigg1.344 mol CH3OHkg waterparenrightbigg×(0.400 kg water)×parenleftbigg32.0 g CH3OHmol CH3OHparenrightbigg= 17.2 g CH3OH0035.0 pointsDissociation of a solid is aided by3.stronginteractionbetweensolventmolecules.4.weak binding of species in the solid andstrong interactions between the solvent andsolute.correctExplanation:Weak intermolecular forces in the solutefacilitate separation of its particles and strongattractive forces between solute and solventfacilitate dissociation of a solid.00412.0 pointsMethanol (CH3OH) and ethanol (C2H5OH)are common organic solvents.The vaporpressures of pure methanol and pure ethanol
Version 096 – Exam 1 – Fakhreddine – (52395)2at 25◦C are 122.7 torr and 58.9 torr, respec-tively. If the mole fraction of CH3OH in themixture of the two solvents at 25◦C is 0.2,what is the mole fraction of C2H5OH in thevapor phase that is in equilibrium with theliquid mixture?