Tests for ions and hydrogen

Explain the test for halide ions

Halide ions in solutions are detected using silver nitrate solutions. The test solution is acidified using a few drops of dilute nitric acid, and then a few drops of silver nitrate solution are added. Different coloured silver halide precipitates form, depending on the halide ions present:

Explain the test for metal ions

It is possible to use a flame test to detect the presence of an alkali metal ion. You just place the substance in a flame and see what colour the flame goes.

Explain the test for hydrogen

If you hold a lit splint at the open end of a tube containing hydrogen you'll hear a "squeaky pop" which is created by the hydrogen burning quickly with the oxygen in the air.

What do the halide ions give off

Chloride ions give a white precipitate of silver chloride
Bromide ions give a cream precipitate of silver bromide
Iodide ions give a yellow precipitate of silver iodide

What colour flame does metal ions give off?

Lithium gives a red flame
Sodium gives a yellow-orange flame
Potassium gives a lilac flame
Calcium gives a brick red flame
Barium gives an apple green flame