test for cations

• give ways of testing cations

  flame test and producing metal hydroxides from sodium hydroxide
• give cations tested with flame test

  • lithium
  • calcium
  • sodium
  • copper
  • potassium
• give coloured flame of lithium

  crimson
• give coloured flame of calcium

  orange red
• give coloured flame of sodium

  yellow
• give coloured flame of copper

  green
• give coloured flame of potassium

  lilac
• give cations tested by producing metal hydroxides

  • aluminium
  • calcium
  • magnesium
  • iron III
  • iron II
  • copper II
• give coloured precipitate of calcium hydroxide

  white
• give coloured precipitate of magnesium hydroxide

  white
• give coloured precipitate of aluminium

  white to colourless in excess sodium hydroxide
• give coloured precipitate of iron III

  brown
• give coloured precipitate of iron II

  green
• give coloured precipitate of copper II

  blue