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