Question

Ammonia gas on passing through Nessler's reagent gives:

A) white precipitate

B) Brown precipitate

C) lblack precipitate

D) No precipitate
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Answer 1

Answer:

B) brown precipitate

is correct

Answer 2

Answer:

Ammonia gas on passing through Nessler's reagent gives: Brown precipitate

Explanation:

Nessler's reagent is an alkaline solution of K₂HgI₄. On combining potassium iodide with mercuric chloride it is formed. It can be made slightly alkaline by adding NaOH or KOH.  In reaction with gaseous ammonia, it gives brown fumes. And with a solution of ammonia, gives a brown precipitate.

The reaction involved is:

2K₂HgI₄ + 3KOH + NH₃→ [OHg₂.NH₂]I + 7KI + 2H₂O

complex [OHg₂.NH₂]I  is called Iodide of million's base it is a brown precipitate that is insoluble. Hence the answer here is b brown precipitate.