Why the brown ring in the test of HNO3 disappears when the test tube is disturbed

Asked by lovemaan5500 | 23rd Oct, 2017, 05:34: PM

Expert Answer:

When acidified ferrous sulphate solution is added to the solution containing nitrate ions in presence of H2SObrown ring is formed.
The brown ring is formed due to formation of complex sphere. In this complx Fe ion ocillates between +1 and +2 oxidation states.The acidified ferrous sulphate solution added dropwise at the walls of test tube to minimize the disturbance. Even a slight disturbance in the medium destroy the ring.

Answered by Varsha | 24th Oct, 2017, 11:16: AM