EXAM PRACTICE QUESTIONS Chapter 14 1 How many grams of sucrose C12H22O11 must be dissolved in 750 mL of water to prepare a 0 250 molal solution 64 1 g If the mole fraction of CH3OH in a solution with only water is 0 0250 what is the molality of the CH3OH 1 42 m In a home ice cream freezer we lower the freezing point of the water bath surrounding the ice cream by dissolving NaCl in water to make a brine solution A 15 0 brine solution is observed to freeze at 10 888 cid 113 C What is the van t Hoff factor i for this solution 1 94 Indicate by writing yes or no in the blanks below which of the following pairs will form a solution when mixed 2 3 4 KI in CCl4 LiF in water CH3OH in water CH3OH in C6H6 vegetable oil in mineral oil no yes yes no yes 5 What is the vapor pressure of an aqueous solution containing 10 0 w w ethylene glycol 62 0 g mol at 25 cid 113 C PH2O 24 3 torr at 25 cid 113 C 23 5 torr 6 At 25 cid 113 C a solution consists of 0 450 mole pentane C5H14 and 0 250 mol of cyclopentane C5H10 What is the lowering of the vapor pressure of pentane in this solution The vapor pressure of the pure liquids at 25 cid 113 C are 451 torr for pentane and 321 torr for cyclopentane 161 torr 7 When 1 150 grams of an unknown electrolyte dissolves in 10 0 grams of water the solution freezes at 2 16 cid 113 C What is the molecular weight of the unknown compound Kf for water is 1 86 cid 113 C m 99 1 g mol 8 The osmotic pressure of 1 00 L of an aqueous solution of a nonelectrolyte solute is 1 17 atm at 0 00 cid 113 C The density of the solution is 1 09 g mL The chemical formula of the nonelectrolyte is C3H6O3 What is the m m of the nonelectrolyte in the solution 0 431 m m 9 Which solution would produce the lowest freezing point 10 A 0 0490 m aqueous NaBr solution freezes at 0 173 cid 113 C What is the apparent percent 0 075 m sodium sulfate dissociation if NaBr in this solution Kf 1 86 cid 113 C m for water 89 8 NaBr cid 111 Na Br
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