AMMONIUM THIOCYANATE SOLUTION, 0.1 N


                         Preparation                       

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

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 NH 4SCN 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.

Post a Comment

0 Comments