chemistry tests for QA

carbonate (CO₃^2-)

add dilute acid

• effervescence, carbon dioxide produced

chloride (Cl^-) [in solution]

acidify with dilute nitric acid, then add aq silver nitrate

• white ppt

iodide (I^-) [in solution']

acidify with dilute nitric acid, then add aq silver nitrate

• yellow ppt

nitrate (NO₃^-) [in solution]

add aq sodium hydroxide, then aluminium foil, warm carefully

• ammonia gas produced

sulfate (SO₄^2-) [in solution]

acidify with dilute nitric acid, then add aq barium nitrate

• white ppt

aluminium (Al³⁺)

aq NaOH:

• white ppt, soluble in excess — colourless solution

aq NH₃:

• white ppt, insoluble in excess

ammonium (NH₄⁺)

aq NaOH:

• ammonia gas produced on warming

calcium (Ca²⁺)

aq NaOH:

• white ppt, insoluble in excess

aq NH₃:

• no ppt

copper (II) (Cu²⁺)

aq NaOH:

• light blue ppt, insoluble in excess

aq NH₃:

• light blue ppt, soluble in excess — dark blue solution

iron (II) (Fe²⁺)

aq NaOH & aq NH₃:

• green ppt, insoluble in excess

iron (III) (Fe³⁺)

aq NaOH & aq NH₃

• red-brown ppt, insoluble in excess

zinc (Zn²⁺)

aq NaOH & aq NH₃:

• white ppt, soluble in excess

ammonia (NH₃)

turns damp red litmus paper blue

carbon dioxide (CO₂)

gives a white ppt with limewater (ppt dissolves in excess CO₂)

hydrogen (H₂)

“pops” with a lighted splint

oxygen (O₂)

relights a glowing splint

sulfer dioxide (SO₂)

turns aq acidified potassium manganate (VII) (KMnO₄) from purple to colourless