Procedure for preparation and standardization 0.05 M Sodium Arsenite

1. OBJECTIVE
To lay down the procedure for preparation and standardization of 0.05 M Sodium Arsenite

2. SCOPE
This procedure is applicable to Quality Control Department

3. RESPONSIBILITY
• Officer QC
• Manager QC

4. SAFETY INSTRUCTIONS
• Proper handling the apparatus.
• Proper handling the chemicals
• Always wear appropriate personal protective equipment when handling this chemical.

5. PROCEDURE
5.1 PREPARATION
5.1.1 Determine the molecular weight of Sodium Arsenite. The molecular weight of Sodium Arsenite is 129.91 g/mol.
5.1.2 Calculate the amount of Sodium Arsenite needed to prepare the solution. To prepare a 0.05 M solution, you will need 0.05 moles of Sodium Arsenite per liter of solution. Therefore, to prepare 1 liter of solution, you will need:
      0.05 moles/L x 1 L = 0.05 moles
5.1.3 The mass of Sodium Arsenite required can be calculated using the following formula:
      Mass (g) = moles x molecular weight (g/mol)
      Mass (g) = 0.05 moles x 129.91 g/mol
      Mass (g) = 6.496 g
5.1.4 Weigh out 6.496gm of Sodium Arsenite using a balance.
5.1.5 After measuring the required amount, transfer it into a 1 liter volumetric flask.
5.1.6 Add a small amount of distilled water to the flask and swirl to dissolve.
5.1.7 Then fill up the flask with distilled water until the mark and mix well.
5.2 STANDARDIZATION
5.2.1 Transfer about 100 mg, accurately weighed, of reagent-grade sodium chloride, previously dried at 110 for 2 hours, to a 150-mL beaker.
5.2.2 Dissolve in 5 mL of water, and add 5 mL of acetic acid, 50 mL of methanol, and about 0.5 mL of eosin Y TS.
5.2.3 Stir, preferably with a magnetic stirrer, and titrate with the silver nitrate solution.
5.2.4 And calculate the normality by the following formula:

         mg NaCl
N= ——————————————————
         ml AgNO3 x 58.44

6. RELATED DOCUMENTS
N/A

7. DISTRIBUTION INDEX
Original Copy will be retained by Quality Assurance Department.

8. ABBREVIATIONS
Q.C Quality Control Department
TS Test Solution
Gm Gram
ml Milliliter

9. REVISION HISTORY