Chemical Analysis

• Pure substance


  A single element or compound, not mixed with any other substance
• Formulation


  A mixture of compounds in measured quantities that has been designed as a useful product
• Paper chromatography


  1. Draw start line

  2. Place sample on line

  3. Fill beaker with solvent

  4. Hang paper in beaker

  5. Solvent travels up paper

  6. Mark finish line

  7. Dry paper
• Rf value


  Distance moved by the spot / distance moved by solvent
• Rf value of 0.85

  Compound has higher affinity for the solvent than for the paper
• Tests for hydrogen, oxygen, carbon dioxide and chlorine

  • Hydrogen - pop with burning splint
  • Oxygen - glowing splint relights
  • Carbon dioxide - turns limewater milky
  • Chlorine - bleaches damp litmus paper
• Flame test results


  • Lithium - crimson red
  • Sodium - yellow
  • Potassium - lilac
  • Calcium - orange red
  • Copper - green
• Sodium hydroxide tests


  1. Cu2+ - blue precipitate

  2. Fe2+ - dirty green precipitate

  3. Fe3+ - brown precipitate

  4. Al3+, Ca2+, Mg2+ - white precipitates
• Test for carbonate anions

  Add dilute acid, fizzing as CO2 is released
• Test for sulfate anions

  Add BaCl2 solution, white precipitate of BaSO4 forms
• Test for halide anions


  Add AgNO3 solution (acidified with HNO3)

  Chlorides - white precipitate AgCl

  Bromides - cream precipitate AgBr

  Iodides - yellow precipitate AgI
• Instrumental methods


  Accurate, sensitive and rapid methods useful when sample amount is very small
• Flame emission spectroscopy


  Spectroscope measures exact wavelength of light emitted by metal ion

  Intensity of light emitted indicates concentration of metal ion
• Cations


  Positive ions
• Anions


  Negative ions