cation testing

• how do you carry out a flame test?

  1. clean nichrome wire with a blue flame
  2. dip in acid to sterilise and reflame
  3. dip nichrome wire in the sample
  4. place sample in flame - observe colour (use a new nichrome wire each time so the colours do not become mixed.)
• calcium flame colour?

  brick red
• sodium flame colour?

  yellow
• potassium flame colour?

  lilac
• copper flame colour?

  green/blue
• lithium flame colour?

  crimson red
• how do you carry out the cation precipitation reaction?

  1. add a few drops of sodium hydroxide to a beaker
  2. note the colour of the precipitate
  3. add excess sodium hydroxide
• copper precipitate?

  light blue
• iron fe2+ precipitate?

  dirty green
• iron fe3+ precipitate?

  brown
• aluminium, calcium, magnesium precipitate?

  white