Qualitative Analysis (Test For Different Ions) Flashcards
What test can you use to identify different metal cations?
Flame test
What cation produces a red flame?
Lithium
What cation produces a yellow flame?
Sodium
What cation produces a lilac flame?
Potassium
What cation produces a orange-red flame?
Calcium
What cation produces a blue-green flame?
Copper
What can flame photometer improve?
Sensitivity (they can detect smaller amounts)
Accuracy (give values closer to the true values)
Speed
How do you test for metal ions?
Precipitation reactions
Add a few drops at a time of dilute sodium hydroxide solution to the test solution
Different metal ions produce different coloured precipitates
What precipitate colour would Iron (11) show?
Green
What precipitate colour would Iron (111) show?
Brown
What precipitate colour would Copper show?
Blue
What precipitate colour would Calcium show?
White
What precipitate colour would Aluminium show?
White
Because aluminium and allium both produce a white precipitate, how do you distinguish between the two?
Aluminium hydroxide forms a colourless solution over time when excess sodium hydroxide is added but calcium doesn’t
How do you test for ammonium ions?
Add sodium hydroxide solution and gently warm
Hold damp red litmus paper over solution. If ammonia is present/produced, the paper will turn blue.
How do you test for Carbonates?
Add dilute acid
If carbonate is present, there will be bubbles of C02
Test this gas using limewater
How do you test for sulfate ions?
Add dilute HCL (removes any carbonate)
Add a few drops of BaCl2 (Barium chloride)
If sulfate is present, a white precipitate of BaCl2 will form
How do you test for Halide ions?
Add a few drops of nitric acid
Add a few drops of silver nitrate
Record the colour of precipitate formed
What colour will the precipitate be if chloride is present?
White
What colour will the precipitate be if bromide is present?
Cream
What colour will the precipitate be if Iodide is present?
Yellow
