Chemistry » Chemical Analysis

Chemical Analysis

Key Words:

Pure - nothing has been added it's in its natural state. Contains one compound or element.

Formulations - mixtures with a precise purpose.

Chromatography - an analytical method to separate substances in a mixture.

Mobile phase - molecules can move, they are liquid or a gas.

Stationary phase - molecules can't move, they are solid or thick liquid.

Rf value - the ratio between the distance travelled by the dissolved substance and the distance travelled by the solvent.

Tests:

  • Chlorine - turns litmus paper white.
  • Oxygen - glowing splint will relight.
  • Carbon Dioxide - added to limewater turns solution cloudy.
  • Hydrogen - lighted splint will 'pop'.
  • Carbonate ions - add drops of dilute acid, then connect to a tube of limewater. Turns solution cloudy.
  • Sulfate ions - add drops of dilute hydrochloric acid & barium chloride solution. A white precipitate of barium sulfate will form.
  • Halides ions - add drops of dilute nitric acid & silver nitrate solution:
    • Chloride gives a white precipitate of silver chloride.
    • Bromide gives a cream precipitate of silver bromide.
    • Iodide gives a yellow precipitate of silver iodide.
  • Lithium ions - burn a crimson in a flame.
  • Sodium ions - burn yellow in a flame.
  • Potassium ions - burn lilac in a flame.
  • Calcium ions - burn orange-red in a flame.
  • Copper ions - burn green in a flame

Flame Emission Spectroscopy - uses the intensity of light from a flame to produce a line spectrum.


 


PRACTICAL
Calculating R values

Watch the video and have a go at writing out the steps of the practical.

Note paper for practical

PRACTICAL
Identifying Ions

Watch the video and have a go at writing out the steps of the practical.

Note paper for practical


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