CHEM 135 PRACTICE EXAM
1. A solution is prepared by dissolving 20.2 mL of methanol (CH3OH) in
100.0 mL of water at 25 C. The final volume of the solution is 118 mL. The densities of
methanol and water at this temperature are 0.782 g/mL and 1.00 g/mL, respectively. For this
solution, Calculate the percent by mass.: ( mass ofsolute/mass solution ) * 100
= 13.6 %
2. A solution is prepared by dissolving 20.2 mL of methanol (CH3OH) in 100.0mL of water at
25 C. The final volume of the solution is 118 mL. The densitiesof methanol and water at this
temperature are 0.782 g/mL and 1.00 g/mL, respectively. For this solution, Calculate the mole
fraction.: (amount of solute (mol)) / (mol of solute + mol of solvent)
= 8.16 %
3. What mass of sucrose is contained in 355 mL (12 ounces) of a soft drinkthat is 11.5%
sucrose by mass? (Assume a density of 1.04 g/mL.): 355 mL * (1.04g/1mL) = 369.2g * 0.115
=42.5 g
4. A water sample is found to contain the pollutant chlorobenzene witha concentration of 15
ppb (by mass). What volume of this water contains
5.00×102mg of chlorobenzene? (Assume a density of 1.00 g/mL.): ppb = (massof solute / mass
of solution) * 10^9
solve for mass of solutionconvert to L
= 3.3×10^4 L
5. What is the molarity of a 10.5 % by mass glucose (C6H12O6) solution? (Thedensity of the
solution is 1.03 g/mL .): 0.600 M
6. What is the molality of a 10.5 % by mass glucose (C6H12O6) solution? (Thedensity of the
solution is 1.03 g/mL .): 0.651 m
7. What is the correct way to prepare a 1 molar solution of KNO3?
a) Combine 101.1 g KNO3 with 1 L of water.
b.) Combine 101.1 grams of KNO3 with 1 kilogram of water.
c.) Add 101.1 grams of KNO3 to a small volume of water in a 1-L volumetric flask, dissolve
the KNO3, and then fill the flask up to the 1 L mark with water.d.) Add 1 gram KNO3 to 99
grams of water.: c.) Add 101.1 grams of KNO3 to a small volume of water in a 1-L volumetric
flask, dissolve the KNO3, and then fill theflask up to the 1 L mark with water.
1. A solution is prepared by dissolving 20.2 mL of methanol (CH3OH) in
100.0 mL of water at 25 C. The final volume of the solution is 118 mL. The densities of
methanol and water at this temperature are 0.782 g/mL and 1.00 g/mL, respectively. For this
solution, Calculate the percent by mass.: ( mass ofsolute/mass solution ) * 100
= 13.6 %
2. A solution is prepared by dissolving 20.2 mL of methanol (CH3OH) in 100.0mL of water at
25 C. The final volume of the solution is 118 mL. The densitiesof methanol and water at this
temperature are 0.782 g/mL and 1.00 g/mL, respectively. For this solution, Calculate the mole
fraction.: (amount of solute (mol)) / (mol of solute + mol of solvent)
= 8.16 %
3. What mass of sucrose is contained in 355 mL (12 ounces) of a soft drinkthat is 11.5%
sucrose by mass? (Assume a density of 1.04 g/mL.): 355 mL * (1.04g/1mL) = 369.2g * 0.115
=42.5 g
4. A water sample is found to contain the pollutant chlorobenzene witha concentration of 15
ppb (by mass). What volume of this water contains
5.00×102mg of chlorobenzene? (Assume a density of 1.00 g/mL.): ppb = (massof solute / mass
of solution) * 10^9
solve for mass of solutionconvert to L
= 3.3×10^4 L
5. What is the molarity of a 10.5 % by mass glucose (C6H12O6) solution? (Thedensity of the
solution is 1.03 g/mL .): 0.600 M
6. What is the molality of a 10.5 % by mass glucose (C6H12O6) solution? (Thedensity of the
solution is 1.03 g/mL .): 0.651 m
7. What is the correct way to prepare a 1 molar solution of KNO3?
a) Combine 101.1 g KNO3 with 1 L of water.
b.) Combine 101.1 grams of KNO3 with 1 kilogram of water.
c.) Add 101.1 grams of KNO3 to a small volume of water in a 1-L volumetric flask, dissolve
the KNO3, and then fill the flask up to the 1 L mark with water.d.) Add 1 gram KNO3 to 99
grams of water.: c.) Add 101.1 grams of KNO3 to a small volume of water in a 1-L volumetric
flask, dissolve the KNO3, and then fill theflask up to the 1 L mark with water.
