Chapter 13

Types of Mixtures

  • Mixture: Combination of two or more pure substances.
  • Heterogeneous Mixtures: Do not blend smoothly; substances remain distinct.
    • Suspensions: Can be separated by settling or filtration.
    • Colloids: Intermediate particle size; exhibit Brownian motion.
      • Brownian Motion: Constant movement of particles in a colloid.
      • Dispersed Phase: Colloidal particles.
      • Dispersing Medium: The substance the colloidal particles are dispersed in, like water.
  • Homogeneous Mixtures (Solutions): Solute is indistinguishable from solvent.
    • Solute: Substance that dissolves.
    • Solvent: Dissolving medium.
    • Soluble: A solute that can dissolve in a solvent.
    • Insoluble: A solute that cannot dissolve in a solvent.
    • Miscible: Two liquids that mix.
    • Immiscible: Two liquids that do not mix.
  • Tyndall Effect: Light scattering by colloids.

Solution Concentration

  • Concentration: Amount of solute in a solvent or solution.
  • Concentrated Solution: Large amount of solute.
  • Dilute Solution: Small amount of solute.
  • Percent by Mass: \frac{\text{mass of solute}}{\text{mass of solution}} \times 100
  • Percent by Volume: \frac{\text{volume of solute}}{\text{volume of solution}} \times 100
  • Molarity (M): \frac{\text{moles of solute}}{\text{liter of solution}}
  • Molality (m): \frac{\text{moles of solute}}{\text{kilogram of solvent}}
  • Stock Solutions: High concentration solutions diluted for lab use.

Factors Affecting Solvation

  • Solvation: Surrounding solute particles with solvent particles.
  • Hydration: Solvation in water.
  • "Like dissolves like": Polar solvents dissolve polar solutes.
  • Heat of Solution: Net energy change during solvation.
  • Factors Increasing Solvation: Agitation, surface area, temperature.
  • Solubility: Amount of solute that dissolves in a solvent.
  • Saturated Solution: No more solute dissolves; equilibrium.
  • Unsaturated Solution: More solute can dissolve.
  • Supersaturated Solution: Holds more solute than normal at a given temperature; unstable.
  • Henry's Law: Deals with the solubility of a gas in a liquid as a function of pressure.

Colligative Properties of Solutions

  • Colligative Properties: Properties affected by the number of solute particles, not their identity.
  • Electrolytes: Conduct electricity; ionic compounds.
  • Nonelectrolytes: Do not conduct electricity; usually molecular compounds.
  • Strong Electrolytes: Produce many ions in solution.
  • Weak Electrolytes: Produce few ions in solution.
  • Vapor Pressure Lowering: Reduced vapor pressure due to solute particles.
  • Boiling Point Elevation: Increased boiling point due to solute particles.
    • \Delta T = K_b \cdot m
  • Freezing Point Depression: Decreased freezing point due to solute particles.
    • \Delta Tf = Kf \cdot m
    • \Delta T represents the change in temperature.
    • K_f represents the molal freezing point depression constant.
    • K_b represents the molal boiling point elevation constant.
    • m represents molality.