Purification Techniques

Purification Techniques

1. Pure Substances

   • A pure substance is a single substance not mixed with anything else
     • Has fixed boiling and melting points
       • Testing for purity
         • Find the melting point
         • Find the boiling point
         • Paper chromatography

2. Mixtures

   • A mixture contains two or more substances that are not chemically combined
     • Melts and boils at a range of temperatures that are lower(melting) or higher (boiling) than when the substance is pure
   • Can be separated using METHODS OF SEPARATION AND PURIFICATION
     • Separating an insoluble solid from a liquid
       • FIltration
       • Filtration is used to separate an insoluble solid from a liquid
         • Residue is the solid collected in the filter paper
         • Filtrate is the liquid passing through the filter paper
     • Separating a soluble solid from a liquid
       • Crystallisation
         • Crystallisation separates a dissolved solid from a solution as well-formed crystals
           • > temperature, > solubility of solute increases, >solute dissolves
     • Separating Solids
       • Sublimation
         • Sublimation separates a mixture of solids, one of which sublimes
           • Substances that sublime:
             • Some Ammonium compounds
             • Iodine
             • Anhydrous Aluminium Chloride
             • Anhydrous Iron (III) Chloride
             • Dry Ice
     • Separating a liquid from a solution
       • Simple Distillation
         • Simple Distillation separates a pure liquid (or solvent) from a solution of a solute
           • carried out to separate a volatile liquid from a non-volatile liquid
     • Separating immiscible liquid
       • Separating Funnel
         • A Separating funnel is used to separate immiscible liquids
     • Separating miscible liquids
       • Fractional Distillation
         • Fractional distillation separates mixtures of miscible liquids that have boiling points far apart from each other
           • Liquid with lower boiling point will distil first followed by the liquid with the next lowest boiling point and so on
     • Separating components that dissolve in the same solvent
       • Paper Chromatography
         • Chromatography is a method of separating and identifying mixtures
           • Used to
             • identify a substance
             • determine the purity of a substances
             • separating 2 or more substances in a mixture
           • Types
             • Ascending type
             • Descending type
           • The chromatography paper with the separated components is called a chromatogram
             • for colorless substances
               • Chromatogram sprayed with a locating agent
             • Substances on a chromatogram can be identified by their Rf values
               • Distance moved by substance/Distance moved by solvent
           • Principle of Chromatography
             • > soluble the substance, >faster it will be carried by the solvent, >further it will move ahead of the less soluble solutes