Solubility and Concentration

the maximum amount of solute that will dissolve in a specified amount of solvent at a certain temperature
• usually experessed as grams of solute per 100 grams of solvent
• temperature must be specified
• if solute is gas, pressure must also be specified

Concentration

• Concentrated vs. dilute solutions
  • a concentrated solution has a large amount of solute in the solvent
  • a dilute solution has a small amount of solute in the solvent
  • concentrated and dilute are not precise terms as they can vary widely
• Precise means of stating concentration
  1. percentage by volume
     • often used if two liquids are being mixed
  2. percentage by mass
     • can be used when solid is dissolved in liquid
  3. Mass of solute per liter of solution
  4. Molarity
     • moles of solute per liter of solution

  Limits of Solubility

  • saturated solution
    • has dissolved all of the solute it can hold at a specified temperature
    • any additional solute added will not disssolve- it will settle to bottom
  • unsaturate solution
    • can still dissolve more solute at a given temperature
    • this term isn't very precise as many concentrations would be considered unsaturated
  • supersaturated solution
    • contains more solute than a saturated one does at the same temperature
    • made by cooling a then saturated solution
    • the excess solute remains in solution
    • supersaturated solutions are unstable
    • if a tiny crystal of solute is added to the solution, the excess solute crystallizes
  Next lesson: Particles in Solution

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