Chemical Analysis 1

Chemical Analysis 1

1. Chromatography

   • Separating technique that separates substances based on solubility in a particular substance
     • Identifies additives/pesticides in food,dugs & alcohol,water samples for pollution,crime investigation,inks...
   • Paper Chromatography
     • Separates according to size of particle
       • Solvent rises through paper
         • Dissolves sample picture
           • Small particles(more soluble) will travel further than large particles
     • Retention Factor(RF Factor)
       • Used to compare the components of various other samples
         • Rf=distance from the base line to the spot÷distance from base line to solvent front

2. Identification of gases

   • Hydrogen
     • A lighted splint should make a "pop" noise
   • Oxygen
     • A glowing splint will relight
   • Carbon Dioxide
     • Limewater gets cloudy if gas is present
   • Chlorine
     • Makes damp blue litmus paper turn red(indicates chlorine is acidic),then white

3. The Flame Test

   • Place small amount of compound in a nichrome loop which has been cleaned with HCL & heated
     • Dip once again n HCL before taking the metal ion
       • Hold loop in roaring blue flame & flame will change colour
   • Lithium-Crimson
     • Sodium-yellow
       • Potassium-lilac
         • Barium-green
           • Calcium-red
             • Copper-green

4. Metal Hydroxides

   • Solutions of aluminium,calcium & magnesium ions with sodium hydroxide form precipitates
     • Precipitate-Insoluble solid formed in the reaction
     • Copper(II)-blue
       • Iron(II)-green(turns orange brown when left)
         • Iron(III)-orange-brown

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