11.4 Colligative Properties

What is the microscopic explanation for the macroscopic behavior illustrated in the reference?

A solution of potassium nitrate, an electrolyte, and a solution of glycerin (C₃H₅(OH)₃), a nonelectrolyte, both boil at 100.3 °C. What other physical properties of the two solutions are identical?

What are the mole fractions of HNO₃ and water in a concentrated solution of nitric acid (68.0% HNO₃ by mass)?

(a) Outline the steps necessary to answer the question.

(b) Answer the question.

Calculate the mole fraction of each solute and solvent:

(a) 0.710 kg of sodium carbonate (washing soda), Na₂CO₃, in 10.0 kg of water—a saturated solution at 0 °C

(b) 125 g of NH₄NO₃ in 275 g of water—a mixture used to make an instant ice pack

(c) 25 g of Cl₂ in 125 g of dichloromethane, CH₂Cl₂

(d) 0.372 g of tetrahydropyridine, C₅H₉N, in 125 g of chloroform, CHCl₃

What is the difference between a 1 M solution and a 1 m solution?

What is the molality of nitric acid in a concentrated solution of nitric acid (68.0% HNO₃ by mass)?

(a) Outline the steps necessary to answer the question.

(b) Answer the question.

Calculate the molality of each of the following solutions:

(a) 0.710 kg of sodium carbonate (washing soda), Na₂CO₃, in 10.0 kg of water—a saturated solution at 0°C

(b) 125 g of NH₄NO₃ in 275 g of water—a mixture used to make an instant ice pack

(c) 25 g of Cl₂ in 125 g of dichloromethane, CH₂Cl₂

(d) 0.372 g of tetrahydropyridine, C₅H₉N, in 125 g of chloroform, CHCl₃

A 13.0% solution of K₂CO₃ by mass has a density of 1.09 g/cm³. Calculate the molality of the solution.

Assuming ideal solution behavior, what is the boiling point of a solution of 115.0 g of nonvolatile sucrose, C₁₂H₂₂O₁₁, in 350.0 g of water?

(a) Outline the steps necessary to answer the question

(b) Answer the question

Assuming ideal solution behavior, what is the freezing temperature of a solution of 115.0 g of sucrose, C₁₂H₂₂O₁₁, in 350.0 g of water?

(a) Outline the steps necessary to answer the question.

(b) Answer the question.

Assuming ideal solution behavior, what is the osmotic pressure of an aqueous solution of 1.64 g of Ca(NO₃)₂ in water at 25 °C? The volume of the solution is 275 mL.

(a) Outline the steps necessary to answer the question.

(b) Answer the question.

A solution containing 5.00 g of a compound dissolved in 25.00 g of carbon tetrachloride (bp 76.8 °C; K_b = 5.02 °C/m) exhibits a normal boiling point of 81.5 °C. Assuming ideal solution behavior, what is the molar mass of the compound?

(a) Outline the steps necessary to answer the question.

(b) Solve the problem.

A 1.0 m solution of HCl in benzene has a freezing point of 0.4 °C. Is HCl an electrolyte in benzene? Explain.

A 12.0-g sample of a nonelectrolyte is dissolved in 80.0 g of water. The solution freezes at −1.94 °C. Assuming ideal solution behavior, calculate the molar mass of the substance.

Calculate the boiling point elevation of 0.100 kg of water containing 0.010 mol of NaCl, 0.020 mol of Na₂SO₄, and 0.030 mol of MgCl₂, assuming complete dissociation of these electrolytes and ideal solution behavior.

A sample of sulfur weighing 0.210 g was dissolved in 17.8 g of carbon disulfide, CS₂ (K_b = 2.34 °C/m). If the boiling point elevation was 0.107 °C, what is the formula of a sulfur molecule in carbon disulfide (assuming ideal solution behavior)?

Lysozyme is an enzyme that cleaves cell walls. A 0.100-L sample of a solution of lysozyme that contains 0.0750 g of the enzyme exhibits an osmotic pressure of 1.32 $\times$ 10⁻³ atm at 25 °C. Assuming ideal solution behavior, what is the molar mass of lysozyme?

The osmotic pressure of human blood is 7.6 atm at 37 °C. What mass of glucose, C₆H₁₂O₆, is required to make 1.00 L of aqueous solution for intravenous feeding if the solution must have the same osmotic pressure as blood at body temperature, 37 °C (assuming ideal solution behavior)?

Assuming ideal solution behavior, what is the boiling point of a solution of NaCl in water if the solution freezes at −0.93 °C?

The vapor pressure of methanol, CH₃OH, is 94 torr at 20 °C. The vapor pressure of ethanol, C₂H₅OH, is 44 torr at the same temperature.

(a) Calculate the mole fraction of methanol and of ethanol in a solution of 50.0 g of methanol and 50.0 g of ethanol.

(b) Ethanol and methanol form a solution that behaves like an ideal solution. Calculate the vapor pressure of methanol and of ethanol above the sol…

Meat can be classified as fresh (not frozen) even though it is stored at −1 °C. Why wouldn’t meat freeze at this temperature?

A sample of HgCl₂ weighing 9.41 g is dissolved in 32.75 g of ethanol, C₂H₅OH (K_b = 1.20 °C/m). The boiling point elevation of the solution is 1.27 °C. Is HgCl₂ an electrolyte in ethanol? Show your calculations.