Burdge_6e_PPT_Ch13_ACCESS_NB Corrected

Chapter Overview

  • Chapter 13: Physical Properties of Solutions

  • Content Areas:

    • 13.1 Types of Solutions

    • 13.2 The Solution Process

    • 13.3 Concentration Units

    • 13.4 Factors That Affect Solubility

    • 13.5 Colligative Properties

    • 13.6 Calculations Using Colligative Properties

    • 13.7 Colloids

13.1 Types of Solutions

Definitions

  • Saturated Solution: Maximum amount of solute dissolved at specific temperature.

    • Solubility: Amount of solute dissolved in a saturated solution at a given temperature.

  • Unsaturated Solution: Less solute than the solvent can dissolve.

  • Supersaturated Solution: More solute than in a saturated solution is dissolved.

Examples of Solubility

  • Example: Solubility of NaCl in water at 20°C = 36 g/100 mL.

  • Solubility can change with temperature; different solutes and solvents will have differing solubility.

Types of Solutions (Table 13.1)

  • Gas in Gas: Air

  • Gas in Liquid: Carbonated water

  • Gas in Solid: H2 gas in palladium

  • Liquid in Liquid: Ethanol in water

  • Liquid in Solid: Saltwater

  • Solid in Solid: Brass (Cu/Zn)

13.2 The Solution Process

Solution Formation

  • Solvation: Process of solute molecules being surrounded by solvent molecules.

Intermolecular Forces and Solubility

  • Importance of intermolecular forces:

    1. Solute-solute interactions

    2. Solvent-solvent interactions

    3. Solute-solvent interactions

Thermicity in Solutions

  • Exothermic process encourages dissolution, endothermic discourages it with entropy being a crucial factor.

  • "Like dissolves like": Similar types of intermolecular forces increase solubility between solute and solvent.

Example of Miscibility

  • CCl4 and C6H6 are miscible due to similar nonpolar forces.

13.3 Concentration Units

Common Concentration Units

  • Molarity (M): moles of solute/liters of solution

  • Molality (m): moles of solute/kg of solvent

  • Percent by Mass: (mass of solute/mass of solution) x 100%

Comparison of Units

  • Molarity is easier to measure but varies with temperature, whereas molality does not.

Sample Problem 13.2

  • Solution prepared with 170.1 g of glucose in 1 liter of solution finds:

    • (a) Molality

    • (b) Percent by mass

    • (c) Parts per million

13.4 Factors That Affect Solubility

Temperature

  • Solubility of many salts increases with temperature.

Pressure

  • Henry’s Law: Gas solubility in a liquid is proportional to the pressure of that gas over the solution.

    • Formula: c = kP (where c = concentration, P = pressure).

13.5 Colligative Properties

Definitions & Effects

  • Properties depend on the number of solute particles, not their nature.

  • Vapor-pressure lowering: Vapor pressure decreases when non-volatile solute is added.

  • Boiling-point elevation: A solute raises the boiling point of the solvent.

  • Freezing-point depression: A solute lowers the freezing point of the solvent.

Calculation Examples

  • Sample Problem 13.5: Calculate vapor pressure over a solution of glucose in water.

13.6 Calculations Using Colligative Properties

Key Points

  • Colligative properties provide the means to determine molar mass.

  • Used to determine percent dissociation for electrolytes—less than expected indicates incomplete dissociation.

13.7 Colloids

Definition

  • Intermediate between true solutions and heterogeneous mixtures, consisting of larger particles suspended in another medium.

Types of Colloids

  • Aerosols, foams, emulsions, sols, gels.

Tyndall Effect

  • The scattering of light by colloidal particles indicates their presence.

Hydrophilic vs Hydrophobic Colloids

  • Examples include how proteins fold in water, often stabilizing with adsorbed ions to prevent clumping.