Solution Notes

Solution

  • A homogeneous mixture of two or more substances, frequently (but not necessarily) a liquid.

Parts of a Solution

  • Solvent: The substance that does the dissolving.
  • Solute: The substance that is dissolved.
    • Example: Water is the solvent, and salt is the solute.
    • Depiction of Na+ and Cl- ions in a solution.

Like Dissolves Like

  • A rule based on polarity to determine if a substance will dissolve or to choose a solvent.

Common Polar Substances

  • Polar solvents dissolve polar solutes.
    • H2O (Universal Solvent) dissolves Salts
    • Methanol dissolves Sugars
    • Ammonia dissolves Lime

Electrolytes

  • Substances that conduct electricity when dissolved.
  • Examples:
    • Gatorade

Common Non-Polar Substances

  • Non-polar substances dissolve other non-polar substances.
    • Benzene dissolves Rubber
    • Acetone dissolves Nail Polish
    • Carbon Tetrachloride dissolves Fats

Types of Solutions

  • Suspension: A solution where the solute particle size is so large that it will settle out if not constantly agitated.

Types of Solutions (cont.)

  • Colloids: Solutions with intermediate-sized solute particles.
    • Tyndall Effect: Particles in a colloid are large enough to scatter light when in a transparent medium.

Types of Solutions (cont.)

  • Unsaturated: Less solute than needed to occupy all available space in the solvent.
  • Saturated: Every available space in the solvent is occupied.
  • Supersaturated: More solute than the solvent can hold.

Miscibility

  • Miscible: Two liquids will mix to form a new solution.
    • Example: Soda and Grenadine (Shirley Temple).
  • Immiscible: Two liquids will separate upon joining.
    • Example: Oil and water.
  • The "like dissolves like" rule applies.

Solution Concentration

  • Describes the amount of solute in a solution per volume.
  • Generally measured in molarity for chemistry.

Molarity

  • Measures the amount of a solute per unit volume of solution.
  • M=moles soluteL solutionM = \frac{\text{moles solute}}{\text{L solution}}
  • moles=mass (g)molar mass (g/mol)\text{moles} = \frac{\text{mass (g)}}{\text{molar mass (g/mol)}}

Dilutions

  • A solution of lower concentration is made from one of a higher concentration by adding more solvent.

Dilution Equation

  • M<em>1V</em>1=M<em>2V</em>2M<em>1V</em>1 = M<em>2V</em>2
  • C<em>1V</em>1=C<em>2V</em>2C<em>1V</em>1 = C<em>2V</em>2
  • Where:
    • M = Molarity
    • V = Volume
    • C = Concentration

Serial Dilutions

  • A sequential dilution of a solution with equal increments of change in concentration between each step.
  • Used to develop a concentration curve for determining concentration in an unknown.