C3 Forensic science Flashcards
What colour does barium burn?
Green
What colour does lithium burn?
Crimson
What colour does potassium burn?
Lilac
What colour does calcium burn?
Red
What colour does sodium burn?
Yellow
When Fe2+ and sodium hydroxide react what colour precipitate forms?
Green
When CU2+ and sodium hydroxide react what colour precipitate forms?
Blue
When Ca2+ and sodium hydroxide react what colour precipitate forms?
White
When Fe3+ and sodium hydroxide react what colour precipitate forms?
Brown
When Al3+ and sodium hydroxide react what colour precipitate forms?
White (initially) then it redissolves in excess NaOH to form a colourless solution
When Mg2+ and sodium hydroxide react what colour precipitate forms?
White
How do you test for a carbonate ion?
React the substance with a dilute acid, pass the gas through limewater and see if it goes cloudy
acid + carbonate –> salt + water + CO2
And CO2 turns limewater cloudy
How can you test for halide ion?
Add dilute nitric acid, then silver ntrate solution
What ion gives a white precipitate when dilute nitric acid, then silver nitrate solution is added
Chloride
What ion gives a cream precipitate when dilute nitric acid, then silver nitrate solution is added
Bromide
What ion gives a yellow precipitate when dilute nitric acid, then silver nitrate solution is added
Iodide
How do you test for sulfate ions?
Add dilute HCl, then a barium chloride solution.
If a white precipitate of barium sulfate forms the original compound was a sulfate
What ion burns green?
Barium
What ion burns yellow?
Sodium
What ion burns lilac?
Potassium
What ion burns red?
Calcium
What ion burns crimson?
Lithium
What do you need to do before conducting a flame test?
Clean the wire loop you want to use to put the sample on in hydrochloric acid then rinse it using distilled water to prevent contamination
When ion forms a white precipitate when reacted with sodium hydroxide?
Calcium or Magnesium or Aluminium
When ion forms a blue precipitate when reacted with sodium hydroxide?
Copper
When ion forms a green precipitate when reacted with sodium hydroxide?
Fe2+
When ion forms a brown precipitate when reacted with sodium hydroxide?
Fe3+
How do you test to see if a white precipitate formed during a reaction between an ion and sodium hydroxide is Aluminium?
You wait and see if it redissolves in NaOH to form a colourless solution