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0.1 N Ferrous Sulfate Preparation: A Step-by-Step Guide

Ferrous sulfate is a widely used chemical in laboratories and industries, particularly for redox titrations. Preparing a 0.1 N (normal) solution requires precision to ensure accuracy. Below is a detailed guide on how to prepare 0.1 N ferrous sulfate solution efficiently.

Materials Required
– Ferrous sulfate heptahydrate (FeSO₄·7H₂O)
– Distilled water
– Sulfuric acid (H₂SO₄)
– Volumetric flask (1 L)
– Stirring rod
– Analytical balance

Step-by-Step Preparation

1. Calculate the Required Quantity
The molecular weight of FeSO₄·7H₂O is 278.01 g/mol. For a 0.1 N solution (where normality = molarity × n-factor), the n-factor for ferrous sulfate is 1 (Fe²⁺ → Fe³⁺).
– Formula: Weight (g) = Normality × Molecular Weight × Volume (L)
– Calculation: 0.1 × 278.01 × 1 = 27.801 g

2. Weigh the Ferrous Sulfate
Accurately weigh 27.801 g of FeSO₄·7H₂O using an analytical balance.

3. Dissolve in Distilled Water
Transfer the weighed ferrous sulfate into a 1 L volumetric flask. Add about 500 mL of distilled water and stir until completely dissolved.

4. Add Sulfuric Acid
To prevent oxidation of Fe²⁺ to Fe³⁺, add 2-3 mL of dilute sulfuric acid (1:5 ratio with water).

5. Dilute to the Mark
Top up the solution with distilled water to the 1 L mark. Mix thoroughly to ensure uniformity.

6. Storage
Store the solution in an amber bottle to minimize light-induced oxidation. Use freshly prepared solution for best results.

Applications of 0.1 N Ferrous Sulfate
– Used in redox titrations (e.g., dichromate titrations).
– Acts as a reducing agent in chemical analysis.
– Essential in water treatment and soil testing.

Conclusion
Preparing 0.1 N ferrous sulfate requires precise measurements and proper storage to maintain stability. Follow these steps for an accurate and reliable solution. For long-term use, periodic standardization is recommended.

By following this guide, you can ensure a high-quality 0.1 N ferrous sulfate solution for laboratory and industrial applications.