seperating mixtures

• Some useful terms when discussing mixtures


  • Solution: A mixture of a liquid (solvent) and one or more dissolved solids (solutes)
  • Solvent: A liquid that dissolves certain solutes to make a solution
  • Solute: A solid that can be dissolved in solvent to make a solution
  • Soluble: Can be dissolved in a given solvent
  • Insoluble: Can not be dissolved in a given solution
• Separations are techniques used to split up mixtures into their different components. The types of separation used to accomplish this will depend on the states of matter in which we find the mixtures components.
• For mixtures containing liquids and insoluble solids components, the separation technique used is


  • Filtration
• For mixtures containing liquids (solvents) and soluble (solutes), the separation techniques used are


  • Evaporation
  • Crystallization
  • Distillation
• For liquid-liquid mixtures containing multiple different liquids, a range of techniques, such as Fractional distillation, can be used depending on the properties of the liquids involved.
• Filtration


  1. Filter paper is folded into a cone, and inserted into the neck of a filter funnel

  2. This is placed into a conical flask

  3. The mixture is slowly poured into the filter funnel

  4. The filter paper allows liquids to pass through, but prevents solids from passing through

  5. The insoluble solid (called the residue) and liquid (called the filtrate) are separated
• Distillation


  1. The solution is poured into a round-bottomed flask, connected to a water-cooled condenser in a closed system

  2. The solution is heated, causing the liquid solvent to boil and turn from liquid to gas

  3. The gas passes through the condenser, is cooled, and condenses back into a liquid (called the distillate), which is collected

  4. The solid solute remains as residue on the inside of the round-bottomed flask
• Evaporation


  1. The solution is poured into an evaporating basin and heated

  2. The liquid solvent boils off, leaving the solid solute as residue in the evaporating basin
• Crystallisation


  1. The solution is poured into an evaporating basin and gently heated, causing liquid solvent to evaporate, until crystals start to form

  2. The evaporating basin is then removed from the heat and allowed to slowly cool, encouraging the formation of crystals of the solute in residual solution

  3. Once cool, any remaining solution can be removed by filtration, and the crystals patted dry
• Fractional Distillation


  1. The mixture of liquids is poured into a round-bottomed flask, connected to a water-cooled condenser with a thermometer

  2. The mixture is heated, and the temperature of the mixture reaches a point where it equals the lowest boiling point in the mixture

  3. The liquid with that boiling point in the mixture turns into a gas and passes through the condenser, where it is cooled and condenses back into a liquid (referred to as a "fraction")

  4. This is repeated until all of the liquids in the mixture have been separated by their boiling point
• Chromatography can be used to separate mixtures according to the solubility of the components. One common technique is paper chromatography.
• Mixture


  Two or more substances that occupy the same space but are not chemically bonded together
• Solute


  A solid that dissolves in a liquid
• Solvent


  The liquid that dissolves the solute
• Separating a mixture of sand and salt water


  1. Use filtration to separate the sand from the salt water solution

  2. Use distillation to separate the water from the salt water solution