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Q.

What is Nessler's Reagent? How it is prepared in the laboratory?

Asked by dare devil, 07 Nov '09 08:10 pm
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Answers (3)

 
1.

Nesslers reagent is named after Julius Nessler and is used to detect small amounts of ammonia. It is a 0.09 mol/L solution of potassium tetraiodomercurate(II) (K2[HgI4]) in 2.5 mol/L potassium hydroxide. A yellow coloration indicates the presence of ammonia: at higher concentrations, a brown precipitate may form. Nessler's reagent is prepared from potassium iodide and mercury(II) iodide. A hot concentrated solution of mercury(II) chloride is added to concentrated solution of potassium iodide, until the precipitate of mercury(II) iodide stops dissolving. The liquid is filtered, and potassium hydroxide and a further bit of mercury(II) chloride solution are added. The resulting solution is then cooled and diluted to required concentration

Source wikipedia
Answered by Deepak Joshi, 07 Nov '09 09:30 pm

 
  
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Take mercuric chloride solution (HgCl2 is readily soluble in water)To this add KI solution till the red ppt formed dissolves. Add a bit of NaOH solutin. This is Nessler's used to detect presence of Ammonia released from ammo. compounds.
Answered by Anand Agarwal, 09 Nov '09 01:18 am

 
  
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Take mercuric chloride solution (HgCl2 is readily soluble in water)To this add KI solution till the red ppt formed dissolves. Add a bit of NaOH solutin. This is Nessler's used to detect presence of Ammonia released from ammo. compounds.
Answered by Arakuzha Ramachandran, 08 Nov '09 02:21 pm

 
  
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