Preparation and Standardization of 0.1M Ammonium Thiocyanate

1.0 OBJECTIVE 

To lay down the procedure Preparation and Standardization of 0.1M Ammonium Thiocyanate

2.0 SCOPE

This SOP is applicable to Preparation and Standardization of 0.1M Ammonium Thiocyanate in company.

3.0 BACKGROUND 

NIL

4.0 RESPONSIBILITY

4.1 QC-Chemist 

4.2 Head-QC

5.0 PROCEDURE

5.1 Requirements:

5.1.1 Glassware: Burette, burette stand, conical flask, volumetric pipette, beaker, volumetric flask, funnel, glass rod, and wash bottle, etc.

5.1.2 Chemicals: LR grade ammonium thiocyanate (NH4SCN), silver nitrate (AgNO3), nitric acid (HNO3), and ferric ammonium sulphate (NH4Fe(SO4)2), etc.

5.2 Solutions Preparation:

5.2.1 0.1M Silver Nitrate Solution: Prepare a 0.1 M Silver nitrate stock solution by dissolving 1.7 g of Silver nitrate into 100 ml of water.

5.2.2  2M nitric acid : Dilute 126 ml of nitric acid with sufficient water to produce 1000 ml

5.3 Preparation of 0.1M Ammonium Thiocyanate

Dissolve 7.612 g in sufficient water to produce 1000 ml

5.4 Standardization
To 20 ml of 0.1M silver nitrate VS add 25 ml of water, 2 ml of 2M nitric acid and 2 ml of ammonium iron(III) sulphate solution R2 and titrate with the ammonium thiocyanate solution until a reddish yellow colour is obtained.

Each ml of 0.1M silver nitrate VS is equivalent to 7.612 mg of NH4SCN.

Perform a duplicate and calculate the molarity factor (MF)

Note down the average value

5.5 Calculation :

MF = W/ 0.07612 x V      


Note:
1) Restandardise before use
2) Discard the solution after 30 days.
3) For storage and labeling follow the general procedure.