Untitled - Kelly Walsh High School

Solutions 185
3. All methods of numerically expressing the concentration of a solution contain
a term in the denominator referring to the entire solution except
a. mass percentage b. molarity c. molality
d. mole fraction e. volume percentage
4. During a dilution, the one factor that remains constant is
a. the quantity of solute b. the quantity of solvent
c. the volume d. the density e. the osmotic pressure
5. Raoult’s law, osmotic pressure, and freezing point depression calculations
use, without conversion, which of the following respective concentration
units
a. molarity, molality, and mole fraction
b. mole fraction, molarity, and molality
c. mole fraction, molality, and molarity
d. molarity, mole fraction, and molality
e. molality, molarity, and mole fraction
6. The simplest way to distinguish a colloid from a solution is
a. the Tyndall effect b. the osmotic pressure
c. the density d. the vapor pressure e. the freezing point
7. A solution is prepared by dissolving 10.0 g of table salt (sodium chloride),
and 15.0 g of cane sugar (sucrose) in 500.0 g of water. Calculate the mass
percent of the table salt in the solution.
8. Determine the molality of ethanol, C 2H 5OH, in a solution prepared by
adding 50.0 g of ethanol to 250.0 g of water.
9. What is the vapor pressure of a solution made of chloroform, CHCl 3, in carbon
tetrachloride, CCl 4? The mole fraction of chloroform is 0.250. At 25°C
the vapor pressure of chloroform is 197 torr, and the vapor pressure of carbon
tetrachloride is 114 torr.
10. Determine both the freezing point and boiling point of a 1.50 m aqueous
solution of ammonium phosphate, (NH 4) 3PO 4. Pure water freezes at 0.00°C
and boils at 100.00°C. K f for water is 1.86°C/m and its K b is 0.52°C/m.
11. A solution prepared by dissolving 6.95 10 3 g of protein in 0.0300 L of
water has an osmotic pressure of 0.195 torr at 25°C. Assuming the protein
is a nonelectrolyte, determine the molar mass of the gene fragment.
ANSWER KEY
1. Like dissolves like 2. d 3. c 4. a 5. b 6. a
(10.0 g table salt)
7. Mass%
100% 1.90%
(10.0 15.0 500.0) g solution