Chapter Summary/Important Terms

• Types of Solutions

• Expressing Concentrations

Terminology

• Suspension or Mechanical Mixture

  • A Heterogenous mixture of two or more substances

    • ex- salt and water

  • Macroscopic properties are different at different locations within the sample.

    • The sizes, shapes, and concentrations of particles can vary.

  • In some cases, components can be separated through filtration.

• Solution or Homogeneous Mixture

  • A Homogeneous mixture of two or more substances.

    • ex- sugar and water

  • Macroscopic properties do not vary within the sample.

  • Components cannot be separated through filtration.

  • Components can be separated by methods that alter intermolecular forces.

    • ex- distillation and chromatography

  • No components are large enough to scatter visible light.

• Solvent: The substance that is more plentiful in a solution.

• Solute: The substance that is less plentiful in a solution.

Saturated Solution

• When the solvent has dissolved the maximum amount of solute possible at a certain temperature, some solid particles remain undissolved.

• This is an equilibrium system where solid particles continually dissolve in the solvent and dissolved particles fall out of solution.

Types of Solutions

• Liquid - Liquid SOlutions

  • Differences in intermolecular forces can cause the solutions volume to differ from the sum of the voles before mixing.

  • Forms strong london dispersion forces of attraction for one another.

• Solid - Liquid Solutions

  • Many Ionic compounds dissolve in polar solvents (ion-dipole)

  • Polar solids, such as glucose, dissolve in polar solvents. (Dipole-Dipole or H-Bonds).

  • Non-Polar solids, such as mothballs, dissolve in non-polar solvents. (Dispersion)

• Gas - Liquid Solutions

  • * Carbonated drinks

  • Oxygen gas dissolves in water

• Gas - Gas SOlutions

  • Gases are always infinitely soluble in one another.

• Gas - Solid Solutions

  • H2 gas can occupy the spaces between some metal atoms such as iron, and palladium.

• Solid - Solid Solutions

  • Formed by melting, mixing, and solidifying.

  • ex- Steel & Copper

Properties of Steel

• Pure iron lacks directional bonds.

• Steel is more rigid, less malleable and less ductile than pure iron, as a result of the strong directional bonds that form between carbon and iron atoms.

• The density of steel is greater than that or pure iron, as interstitial atoms do not expend the lattice by much.

Expressing Concentration

Two methods for expression concentration:

1. Molarity (M) = Moles Solute/Liters Solution

2. Mole Fractions = X_a = (moles A)/(Moles A + Moles B + … + moles Z)

• Molarity can change with temperature

• Mole fractions do not change with temperature