PRACTICAL CHEMISTRY
37325
Conc. \(HN{O_3}\) is added before proceeding to test for group III members. This is to
1 Oxidise any remaining \({H_2}S\)
2 Convert ferrous ion into ferric ion
3 Form nitrates which give granular ppts
4 Increase ionisation of ammonium hydroxide
Explanation:
(b) \(HNO_3\) oxidises \({Fe_2}^+\) to \({Fe_3}^+\) otherwise \({Fe_2}^+\) is not completely precipitated as hydroxide