JEE Main202226 Jun 2022Morning ShiftChemistryPractical ChemistryActual
Which statement is not true with respect to nitrate ion test?
Options
- AA dark brown ring is formed at the junction of two solutions.
- BRing is formed due to nitroferrous sulphate complex.
- CThe brown complex is Fe H 2 O 5 NO SO 4
- DHeating the nitrate salt with conc. H 2 SO 4 , light brown fumes are evolved.
Correct answer
B. Ring is formed due to nitroferrous sulphate complex.
Step-by-step solution
Brown ring test is usually carried out by adding dilute ferrous sulphate solution to an aqueous solution containing nitrate ion, and then carefully adding concentrated sulphuric acid along the sides of the test tube. A brown ring at the interface between the solution and sulphuric acid layers indicates the presence of nitrate ion in solution. NO 3 − + H 2 SO 4 → HNO 3 + HSO 4 − 6 FeSO 4 + 3 H 2 SO 4 + 2 HNO 3 → 3 Fe 2 SO 4 3 + 2 NO + 4 H 2 O NO + FeSO 4 + 5 H 2 O → Fe H 2 O 5 NO SO 4 (