Question

The function of boiling the sodium extract with conc. $HN{O}_3$ before testing the halogen is:

• A. to convert $F{e}^{++}$ into $F{e}^{+++}$
• B. to make solution clear
• C. to make solution acidic
• D. to destroy cyanide and sulphide ions

Answer 1

Answer: (D)

to destroy cyanide and sulphide ions

If an organic compound contains nitrogen or sulphur, these elements form $NaCN$ and sodium sulphide with sodium metal. So these may interfere in the extraction of Na metal. In order to remove sodium cyanide and sodium sulphide, sodium fusion extract are boiled with concentrated $HN{O}_3$.