Cations/Anions/Flame Test

ammonia, NH₃

turns damp red litmus paper blue

carbon dioxide, CO₂

turns limewater milky

chlorine, Cl₂

bleaches damp litmus paper

hydrogen, H₂

‘pops’ with a lighted splint

oxygen, O₂

relights a glowing splint

sulfur dioxide, SO₂

turns acidified aqueous potassium manganate(VII) from purple to colourless

lithium, Li⁺

red

sodium, Na⁺

yellow

potassium, K⁺

lilac

calcium, Ca²⁺

orange-red

barium, Ba²⁺

light green

copper(II), Cu²⁺

blue-green

Aluminium, Al³⁺

white ppt, soluble in excess, giving a colourless solution # white ppt, insoluble in excess

Ammonium, NH₄⁺

ammonia produced on warming

Calcium, Ca²⁺

white ppt, insoluble in excess # no ppt, or very slight white ppt

Chromium(III), Cr³⁺

green ppt, soluble in excess, giving a grey-green solution # grey-green ppt, insoluble in excess

Copper(II), Cu²⁺

light blue ppt, insoluble in excess # light blue ppt, soluble in excess, giving a dark blue solution

Iron(II), Fe²⁺

green ppt, insoluble in excess, ppt turns brown on standing # green ppt, insoluble in excess

Iron(III), Fe³⁺

red-brown ppt, insoluble in excess # red-brown ppt, insoluble in excess

Zinc, Zn²⁺

white ppt, soluble in excess, giving a colourless solution # white ppt, soluble in excess, giving a colourless solution

Carbonate, CO₃²⁻

add dilute acid, test for carbon dioxide gas # effervescence, carbon dioxide produced

Chloride, Cl⁻ (in solution)

acidify with dilute nitric acid, then add aqueous silver nitrate # white ppt

Bromide, Br⁻ (in solution)

acidify with dilute nitric acid, then add aqueous silver nitrate # cream ppt

Iodide, I⁻ (in solution)

acidify with dilute nitric acid, then add aqueous silver nitrate # yellow ppt

Nitrate, NO₃⁻ (in solution)

add aqueous sodium hydroxide, then aluminium foil, warm carefully # ammonia produced

Sulfate, SO₄²⁻ (in solution)

acidify with dilute nitric acid, then add aqueous barium nitrate # white ppt

Sulfite, SO₃²⁻ (in solution)

add a small volume of acidified aqueous potassium manganate(VII) # the acidified aqueous potassium manganate(VII) changes colour from purple to colourless