Qualitative Analysis

Question 1

gas tests (6)

Answer 1

• Hydrogen (H₂): Extinguishes a lighted splint with a ‘pop’ sound.
• Oxygen (O₂): Relights a glowing splint.
  ~
• Ammonia (NH₃): Turns moist red litmus paper blue.
• Chlorine (Cl₂): Turns moist blue litmus paper red, then bleaches it.
  ~
• Carbon dioxide (CO₂): Forms a white precipitate in limewater.
• Sulfur dioxide (SO₂): Turns acidified potassium manganate(VII) from purple to colorless.

Question 2

h2o test

Answer 2

anhydrous copper ii sulfate: turn blue from white
cobalt ii chloride: turn pink from blue

Question 3

cation tests (8)

Answer 3

Zinc (Zn²⁺):
both sol white ppt

Aluminium (Al³⁺):
aq naoh: sol white ppt
aq nh3: insol white ppt

Lead(II) (Pb²⁺):
aq naoh: sol white ppt
aq nh3: insol white ppt

Calcium (Ca²⁺):
naoh: insol white ppt
nh3: NO PPT

Ammonium (NH₄⁺):
naoh: NO PPT, warm -> nh3

Copper(II) (Cu²⁺):
naoh: insol blue ppt
nh3: sol blue ppt

Iron(II) (Fe²⁺):
both insol green ppt

Iron(III) (Fe³⁺):
both insol reddish-brown ppt

Question 4

anions test (5)

Answer 4

Carbonate (CO₃²⁻):
- dilute nitric acid, effervescence, co2

Chloride (Cl⁻):
- dilute nitric acid, silver nitrate: white ppt (silver chloride).

Iodide (I⁻):
- dilute nitric acid, silver nitrate: yellow ppt (silver iodide).

Sulfate (SO₄²⁻):
- dilute nitric acid, barium nitrate: white ppt (barium sulfate).

Nitrate (NO₃⁻):
- add aluminium, aq. naoh, warm the solution: nh3