Problem Solving

Indicate how many particles are formed when the following solutes dissolve.

1. • sucrose (C12H22O11)

   • magnesium chloride (MgCl2)

   • sodium sulfate (Na2SO4)

   • methanol (CH3OH)

When 5.0 g of CaCl2 dissolves in 50.0 g of water, what is the boiling point of the solution? (Kb Water = 0.512 oC/m)

Find the boiling point of a solution containing 6.0 g benzene, C6H6, in 35 g of napthalene. (Kb of naphthalene = 5.65 oC/m, BP of napthalene = 218 oC)

A solution of 26.0 g of Epsom salt, MgSO4, in 1.5 kg of water is prepared. What is the freezing point of this solution? (Kf water = 1.86 oC/m) What is the boiling point? (Kb Water = 0.512 oC/m)

Calcium chloride is often used to remove ice from roads and sidewalks. Explain how this process works in terms of colligative properties.

Which salt, NaCl or CaCl2, has a greater effect on freezing point?

How much would the boiling point of 1L of water change if you added 20g of NaCl to it?

A solution contains 21.6 g of a nonelectrolyte and 175 g of water. The water freezes at -7.18° C and Kf = 1.86° C/m. Is the nonelectrolyte CH3OH or C2H5OH? Explain how you know.

Calculate the freezing point of a solution made from 32.7 g of propane, C3H8, dissolved in 137.0 g of benzene, C6H6. The freezing point of benzene is 5.50° C and its Kf is 5.12° C/m.

The vapor pressure of water at 20° C is 17.5 torr. What is the vapor pressure of water over a solution containing 300. g C6H12O6 and 455 g of water?

Rank the following solutions from lowest to highest boiling point, a 2.5 m solution of sodium chloride, a 3.5 m solution of magnesium chloride, or a 4.5 m solution of sulfur dioxide?

If an aqueous solution has a boiling point of 102.50 , what’s the effective molality of the solute?