INITIALIZING UNISON
Brown Ring Test
Procedure Steps
1
Add nitrate solution (KNO₃/NaNO₃) to test tube
2
Add freshly prepared FeSO₄ (light green)
3
Tilt test tube, add conc. H₂SO₄ slowly along the wall
4
Brown ring [FeSO₄·NO] forms at the interface
Chemical Reactions
① Nitrate Reduction by H₂SO₄
NO₃⁻ + H₂SO₄ → H⁺ + HSO₄⁻
(acidic medium formed)
(acidic medium formed)
② Fe²⁺ oxidation & NO release
3Fe²⁺ + 4H⁺ + NO₃⁻
→ 3Fe³⁺ + NO↑ + 2H₂O
→ 3Fe³⁺ + NO↑ + 2H₂O
③ Brown Ring Complex Formation
[Fe(H₂O)₆]²⁺ + NO
→ [Fe(H₂O)₅(NO)]²⁺ + H₂O
(Brown nitrosonium complex)
→ [Fe(H₂O)₅(NO)]²⁺ + H₂O
(Brown nitrosonium complex)
④ Overall Ionic Equation
3FeSO₄ + 2H₂SO₄ + 2KNO₃
→ Fe₂(SO₄)₃ + K₂SO₄
+ 2NO + 2H₂O
NO + FeSO₄ → FeSO₄·NO
(Brown Ring ✓)
→ Fe₂(SO₄)₃ + K₂SO₄
+ 2NO + 2H₂O
NO + FeSO₄ → FeSO₄·NO
(Brown Ring ✓)
Legend
FeSO₄ (light green)
KNO₃ solution (clear)
Conc. H₂SO₄ (colourless)
[FeSO₄·NO] Brown Ring
SIMULATION RUNNING
Speed 1×