Chemical analysis

• Lithium ions

  crimson flame
• sodium ions

  yellow flame
• pottassium ions

  lilac flame
• calcium ions

  orange-red flame

  white precipitate
• copper ions

  green flame

  blue precipitate
• to test for metal ions (they are positive ions)


  flame test:

  a clean wire loop, dipped in the sample and put in the blue/ working flame

  only works to test substances with a single metal ion

  precipitation reactions:

  add a few drops of sodium hydroxide (NaOH) solution to a solution of the substance you are testing
• Iron (II) ion


  green precipitate
• Iron (III) ion

  brown precipitate
• Aluminum ion

  white precipitate then redissolves in excess NaOH to form a colourless solution
• Magnesium ion

  white precipitate
• testing for carbonate (CO3 2-) ions (negative)


  carbonate + acid -> salt +water + CO2

  carbon dioxide test by putting the substance in acid and running the gas produced through limewater

  positive result: limewater turns cloudy
• Testing for halide ions (negative)

  add dilute nitric acid (NOH3) and silver nitrate (AgNO3) to the substance
• Chlorine ions

  white precipitate
• bromine ions

  cream precipitate
• iodine ions 


  yellow precipitate
• testing for sulfate (SO4 2-)


  add dilute hydrochloric acid then barium chloride solution (BaCl2)

  A white precipitate after adding barium chloride means the compound contained a sulfate

  the HCl removed any carbonate ions present

  Ba 2+ + SO4 2- -> BaSO4
• chlorine gas test


  turns damp blue litmus red then bleaches it
• oxygen gas test


  relights a glowing splint
• hydrogen gas test


  a lit splint will create a squeaky pop in the presence of hydrogen
• carbon dioxide gas test


  turns limewater from colourless to cloudy