IGCSE Chemistry - Chemical Analysis

Carbonates

It involves adding a few drops of dilute acid to the sample. A gas is given off which turns limewater milky

Chlorine

Add silver nitrate (AgNO3) to the solution. A white precipitate forms.

Bromine

Add a few drops of silver nitrate (AgNO3) to the solution. A creamy-white precipitate forms.

Iodine

Add a few drops of silver nitrate solution. A yellow precipitate forms.

Nitrates

Add sodium hydroxide (NaOH) solution and a small amount of aluminium powder (Al) to the solution. Warm the mixture gently. Gas produced bleaches damp red litmus paper.

Sulfates

Acidify the sample with Nitric acid and add aqueous barium nitrate. A white ppt forms.

Sulfites

Add a dilute acid and warm gently. The gas produced decolourises acidified Potassium Manganate (VII) solution.

Aluminium

Add a few drops of sodium hydroxide solution to the sample. A white ppt is formed, it is soluble in excess and forms a colourless solution.

Ammonium

Add sodium hydroxide (NaOH) and gently heat. The gas produced turns damp red litmus paper blue.

Calcium

When NaOH is added, a white ppt forms which is insoluble in excess. When ammonia is added, a faint white ppt is produced

Chromium (III)

When NaOH is added, a bright green ppt is formed and a green solution is formed in excess solution. When ammonia is added, a grey green ppt is formed which is insoluble in excess.

Copper (II)

When NaOH is added, a light blue ppt is formed, which is insoluble in excess.When ammonia is added, a light blue ppt is formed, which forms a dark blue solution in excess

Iron (III)

When NaOH is added, a red/brown ppt is formed which is insoluble in excess. Ammonia gives the same result.

Zinc

When NaOH is added, a white ppt is formed which dissolves in excess to form a colourless solution, the same is true for ammonia.

Lithium

Red

Sodium

Yellow

Potassium

Lilac

Calcium

Orange

Copper

Blue/Green

Barium

Apple green

sulfur dioxide

Pungent choking mell, colourless, decolourises potassium manganate (VII) solution