Solutions Problems:
Definitions and Units of Concentration:
1. What is the percent by mass of a solution made by dissolving 6.83 g of ethanol to
produce 100. mL of a solution with a density 0.889 g/mL?
2. How many grams of sugar would you need to make 900.0 g of a sugar solution that is
18.6 % by mass sugar?
B. How many grams of water do you need to make 900.0 g of a sugar solution that is
18.6 % by mass sugar?
3. What is the molarity of a solution made by dissolving 22.5 g of Li2SO4 in enough water
to make 650 mL of solution?
4. A solution is made by mixing 100 g ethanol (C2H5OH, Molar Mass 46.08 g)
11.0 g of methanol (CH3OH, Molar Mass 32.04 g) and 500 g of water. What is the
mole fraction of each component in the solution?
5. What is the molality of a solution made by dissolving 25.5 g of Ba(NO3)2 in 150 g of water?
6. Calculate the molarity of a NaNO3 solution that is 17.00 % by mass sodium nitrate and has a density
of 1.1215 g/mL. (Molar Mass sodium nitrate = 85.00 g)
7. Calculate the molarity of a potassium chloride solution that is 0.273 m KCl and has a density
of 1.011 g/mL. (Molar Mass potassium chloride = 74.55 g)
8. Calculate the molality of a Pb(NO3)2 solution that is 0.907 M and has a density of 1.252 g/mL.
Colligative Properties:
9. What is the vapor pressure at 25.0 °C of the solution that results from adding 60.0 g of glucose, a
non-electrolyte (C6H12O6, Molar Mass 180.2 g) to 500 g of water?
For freezing point depression and boiling point elevation, you need constants based on the solvent.
For water:
For benzene:
Freezing point
0.0°C
5.5°C
Kf
1.86 °C/m
4.90 °C/m
Boiling point
100.0°C
80.1°C
Kb
0.512 °C/m
2.53 °C/m
10. What is the freezing point of a solution made by dissolving 4.27 g of sugar (C12H22O11, Molar
Mass =342. g) in 50.0 g of water?
B. What is the boiling point of the above solution?
11. What is the freezing point of a solution made by dissolving 9.75 g of nitrobenzene (C6H5NO2,
Molar Mass =123.0 g) in 175.0 g of benzene?
12. What is the molar mass (molecular weight) of a compound, if a solution made by dissolving 2.12 g
of this compound in 48.92 g of water has a freezing point of – 0.679 °C?