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WORKSHEET 5: CHAPTER 17
1.
A formaldehyde (H2CO) solution is prepared by adding 5.84 g (H2CO) to
100. g H2O. The final volume is 104 mL. What is the molality of this
solution? The mass percent?
2.
A solution was made by adding 42.1 g (0.1885 moles) of CuBr2 to 700.0
mL H2O. At 52.0 ˚C, the density of water is 0.987 g/mL and the vapor
pressure of the pure solvent is 102.1 torr. Assuming that copper
bromide is a strong electrolyte, what is the expected vapor pressure
(torr) of this solution at 52.0 ˚C?
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3.
At 19 ˚C, pure ethanol (C2H5OH) has a vapor pressure of 40.0 mmHg and
pure benzene (C6H6) has a vapor pressure of 70.0 mmHg. Ethanol and
benzene are mixed to prepare a solution with Xethanol = 0.3973. What is
the expected vapor pressure (mmHg) of this solution at 19 ˚C?
4.
When boiling pasta, it’s common to add salt (NaCl – 58.44 g/mol) to the
water. Does this raise or lower the boiling point?
If you were to add 45.0 g NaCl to 1.5 L H2O (density = 0.994 g/mL, Kb =
0.51 ˚C kg/mol), what would you predict the magnitude of ∆Tboiling to be?
Assume complete dissociation of NaCl.