How to prepare & Standardization 0.1 N Ammonium thiocyanate

0.1 N Ammonium thiocyanate (NH4SCN) solution

0.1 N Ammonium thiocyanate (NH4SCN) solution


  Preparation of 0.1 N Ammonium thiocyanate solution  

  • 7.8 g of Ammonium thiocyanate (NH4SCN) to a flask add 100 ml of water, and swirl to dissolve the NH4SCN. 
  • When solution is complete, filter through a hardened filter paper, or other suitable medium. 
  • Dilute the clear filtrate to 1 L with water and mix. Store the solution in a tightly stoppered glass bottle.

  Standardization of 0.1 N Ammonium thiocyanate solution  

  • Measur accurately about 40 ml of freshly standardized 0.1 N Silver nitrate (AgNO3) solution and transfer to a 250-ml conical flask. 
  • Add 50 ml of water, swirl to mix the solution and
  • Add 2 ml of nitric acid (HNO3) and 1 ml ferric ammonium sulfate solution (FeNH4(SO4)2·12H2O, 80 g/L).
  • Titrate the AgNO3 solution with the NH4SCN solution until the first permanent reddish-brown color appears and persists after vigorous shaking for 1 min.


  Calculation                        


Normality of the NH4SCN solution

A = B*C/D

Where:-
A = normality of the NH4SCN solution,
B = millilitres of AgNO3 used,
C = normality of the AgNO3 solution, and
D = millilitres of NH4SCN solution required for titration
of the solution.

Ex-
40 = millilitres of AgNO3 used,
0.09975 = normality of the AgNO3 solution, and
40.1 = millilitres of NH4SCN solution required for titration
of the solution.


A =  40*.09975/40.1 = 0.0995 N





  Stability                     


Re-standardize monthly.

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