Test for positive ions Flashcards
What does flame tests identify?
Metal ions
How do you test for various metal ions?
Putting a substance in a flame and seeing what colour the flame goes
What colour does lithium go?
Crimson
What metal ion is it if the flame turns crimson?
Lithium
What colour does sodium go?
Yellow
What metal ion is it if the flame turns yellow?
Sodium
What colour does potassium go?
Lilac
What metal ion is it if the flame turns lilac?
Potassium
What colour does calcium go?
Red
What metal ion is it if the flame turns red?
Calcium
What colour does barium go?
Green
What metal ion is it if the flame turns green?
Barium
How do you carry out a flame test?
Dip wire in hydrochloric acid and rinse with distilled water
Dip a clean wire loop into the sample of compound
Put the wire in the Blue flame
What are many metal hydroxides?
Insoluble
What do some metal ions form with NaOH?
Coloured precipitate
How can you test metal ions for a precipitate?
Add a few drops of sodium hydroxide to a solution of your compound
What colour precipitate is Calcium?
White
What metal forms a white precipitate?
Calcium
Magnesium
Aluminium - at first
What colour precipitate is copper?
Blue
What metal forms a blue precipitate?
Copper
What colour precipitate is Iron(II)?
Green
What metal produces a green precipitate?
Iron(II)
What colour precipitate is iron(III)?
Brown
What metal produces a brown precipitate?
Iron(III)
What colour precipitate is aluminium?
White at first but redissolves in excess NaOH to form a colourless solution
What colour precipitate is magnesium?
White
