@PROFDOCDIGITALLIBRARIES
ACHM 121 Exam 1
(ANSWERS HIGHLIGTED IN YELLOW)
1. A sample of butane (C4H10) is vaporized at its boiling point. How much energy is required to
vaporize a 142 g sample of butane if its DHvap is 24.3 kJ/mol? The molar mass of butane is 58.12
g/mol.
244 kJ
166 kJ
16.2 kJ
59.4 kJ
200 kJ
2. A solution contains 11% by mass of sodium chloride. This means that __________.
100 g of the solution contains 11 g of sodium chloride
the density of the solution is 11 g/mL
there are 11 g of sodium chloride in in 1.0 mL of this solution
the molality of the solution is 11
100 mL of the solution contains 11 g of sodium chloride
3. As a solid element melts, the atoms become __________ and they have __________ attraction
for one another.
larger, greater
more separated, less
more separated, more
closer together, more
closer together, less
4. Calculate the freezing point of a 0.04250 m aqueous solution of NaNO3. The molal freezing-point-
depression constant of water is
-0.158
0.0425
-0.0790
-0.316
0.0790
5. Colligative properties depend on
, @PROFDOCDIGITALLIBRARIES
The number of particles dissolved
The molar mass of the solute
The chemical properties of the solvent
The Tyndall effect
The chemical properties of the solute
6. Colligative properties of solutions include all of the following except __________.
elevation of the boiling point of a solution upon addition of a solute to a solvent
depression of the freezing point of a solution upon addition of a solute to a solvent
an increase in the osmotic pressure of a solution upon the addition of more solute
tendency to become supersaturated
7. Consider the phase diagram below. If the dashed line at 1 atm of pressure is followed from 100 to
500 °C, what phase changes will occur (in order of increasing temperature)?
melting, followed by vaporization
sublimation, followed by deposition
vaporization, followed by deposition
sublimation, followed by vaporization
No phase change will occur under the conditions specified.
8. Determine the boiling point elevation of a solution that contains 22.5 g of glucose in 500.0 g
ethanol (glucose C6H12O6 molar mass = 180.156 g/mol, ethanol Kb = 1.22°C/m.)
ACHM 121 Exam 1
(ANSWERS HIGHLIGTED IN YELLOW)
1. A sample of butane (C4H10) is vaporized at its boiling point. How much energy is required to
vaporize a 142 g sample of butane if its DHvap is 24.3 kJ/mol? The molar mass of butane is 58.12
g/mol.
244 kJ
166 kJ
16.2 kJ
59.4 kJ
200 kJ
2. A solution contains 11% by mass of sodium chloride. This means that __________.
100 g of the solution contains 11 g of sodium chloride
the density of the solution is 11 g/mL
there are 11 g of sodium chloride in in 1.0 mL of this solution
the molality of the solution is 11
100 mL of the solution contains 11 g of sodium chloride
3. As a solid element melts, the atoms become __________ and they have __________ attraction
for one another.
larger, greater
more separated, less
more separated, more
closer together, more
closer together, less
4. Calculate the freezing point of a 0.04250 m aqueous solution of NaNO3. The molal freezing-point-
depression constant of water is
-0.158
0.0425
-0.0790
-0.316
0.0790
5. Colligative properties depend on
, @PROFDOCDIGITALLIBRARIES
The number of particles dissolved
The molar mass of the solute
The chemical properties of the solvent
The Tyndall effect
The chemical properties of the solute
6. Colligative properties of solutions include all of the following except __________.
elevation of the boiling point of a solution upon addition of a solute to a solvent
depression of the freezing point of a solution upon addition of a solute to a solvent
an increase in the osmotic pressure of a solution upon the addition of more solute
tendency to become supersaturated
7. Consider the phase diagram below. If the dashed line at 1 atm of pressure is followed from 100 to
500 °C, what phase changes will occur (in order of increasing temperature)?
melting, followed by vaporization
sublimation, followed by deposition
vaporization, followed by deposition
sublimation, followed by vaporization
No phase change will occur under the conditions specified.
8. Determine the boiling point elevation of a solution that contains 22.5 g of glucose in 500.0 g
ethanol (glucose C6H12O6 molar mass = 180.156 g/mol, ethanol Kb = 1.22°C/m.)
