Chapter 11 Practice

The normal temperature range of the liquid phase of pure water is 0°C to 100°C. Which of the following solutions will have the largest temperature range for the liquid state?

• 1 M aqueous ethanol solution

• 1 M aqueous potassium bromide solution

• 1 M aqueous acetic acid solution

• 1 M aqueous magnesium bromide solution

• 1 M aqueous magnesium sulfate

What physical property is used to separate the hydrocarbon components in petroleum (crude oil)?

• melting point

• density

• boiling point

• molar mass

• viscosity

Drinking seawater is dehydrating to humans because

• there is a net flow of water molecules out of the cells because the solution is hypertonic.

• there is a net flow of water molecules out of the cells because the solution is hypotonic.

• there is a net flow of hydrated Na+, Cl-, and other ions into the cells because the solution is hypertonic.

• there is a net flow of hydrated Na+, Cl-, and other ions into the cells because the solution is hypotonic.

• the hydrated Na+, Cl-, and other ions block channels in the cell membrane, preventing water molecules from migrating into or out of the cells.

The normal freezing point of benzene (C6H6, 78.12 g/mol) is 5.49°C, and its Kf value is 5.12°C/m. To create a solution with a freezing point of 0.00°C, how many grams of naphthalene (C10H8, 128.2 g/mol) would need to be dissolved in 640.0 g of benzene?

• 5.63 g

• 137 g

• 82.0 g

• 187 g

• 88.0 g

Determine the molal concentration of a table sugar (C12H22O11, 342.3 g/mol) solution in water that has a freezing point of –2.10°C. (Kf = 1.86°C/m for water)

• 1.13 m

• –1.13 m

• 3.91 m

• –3.91 m

• 0.113 m

Determine the vapor pressure of n-pentane on a night when the temperature is 0.0°C. The enthalpy of vaporization of n-pentane is 27.6 kJ/mol, and its boiling point is 36.0°C.

• 228 torr

• 367 torr

• 185 torr

• 479 torr

• 209 torr

Indicate which aqueous solution has the slowest evaporation rate.

• 0.1 M NH4Cl

• 0.2 M K2SO4

• 0.2 M NaOH

• 0.1 M BaCl2

• 0.2 M C6H12O6

Which statement regarding osmotic pressure is NOT correct? Osmotic pressure

• increases with increasing temperature.

• increases with increasing molar concentration of the solute.

• is greater for 0.1 M Na2SO4 than for 0.1 M NaCl.

• depends on the value of the gas constant R.

• is the same for solutions with the same mass percent of solute.

Gasoline is primarily a mixture of hydrocarbons and is sold with an octane rating that is based on a comparison with the properties of isooctane (C8H18), which has an enthalpy of vaporization of 35.8 kJ/mol and a normal boiling point of 98.2°C. Determine the vapor pressure of isooctane on a very hot day when the temperature is 38.0°C.

• 80.6 torr

• 36.7 torr

• 67.8 torr

• 47.9 torr

• 89.3 torr

A solution is prepared by mixing 75 g of methanol (CH3OH, 32.04 g/mol) with 25 g of ethanol (CH3CH2OH, 46.07 g/mol). Use the following data to determine the vapor pressure of this solution at 20°C.

• 69 torr

• 57 torr

• 80 torr

• 73 torr

• 83 torr