Separation Techniques

Separation Techniques

1. Immiscible liquids

   • do not mix into another liquid
     • e.g. oil and water
   • A separating funnel is used to separate immiscible liquids
     • when two immiscible liquids are shaken together, when untouched they will separate out into layers. The denser liquid sinks to the bottom, meanwhile the less dense floats to the top
       • This means that the liquid can be easily separated with a separating funnel with a tap. The tap can be opened to drain off the denser liquid into a beaker
         • oil and water can be separated in this way

2. Miscible liquids

   • They mix well into another liquid
     • e.g. milk and tea
   • Fractional Distillation
     • The process separates out a mixture of miscible liquids
       • The mixtures must have different boiling points
         • If a miscible mixture is heated, then the different liquids will condense at different temperatures and therefore can be collected seperately
           • We can distil liquid air to separate liquid oxygen and argon
             • 1.Air is filtered and dust is removed
               • 2. Air is cooled to roughly -200oC and becomes an miscible mixture of liquids
                 • 3.When cooled water vapour condenses and is removed
                   • 4. CO2 freezes and is removed
                     • 5. Liquefied air enters the fractionating column and is heated slowly
                       • 6. Remaining gases are separated by another fractional distillation column and a different one also is used to separate oxygen and argon