To Prepare Ferrous Sulphate Crystals (Class 10 Chemistry Practical)
To prepare ferrous sulphate crystals by crystallization method and obtain pure crystals suitable for storage
TL;DR: To prepare ferrous sulphate crystals by crystallization method and obtain pure crystals suitable for storage
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Aim: To prepare ferrous sulphate crystals by crystallization method and obtain pure crystals suitable for storage
Materials Required
- Ferrous sulphate solution
- Distilled water
- Evaporating basin
- Glass rod
- Bunsen burner or hot plate
- Filter paper
- Funnel
- Beaker
- Thermometer
Theory
Ferrous sulphate is prepared by dissolving iron filings in dilute sulphuric acid. The solution is then crystallized by cooling to obtain ferrous sulphate heptahydrate crystals. The crystallization process separates pure crystals from impurities. Ferrous sulphate crystals are light green and contain water of crystallization.
Procedure
- Prepare ferrous sulphate solution by reacting iron filings with dilute sulphuric acid
- Filter the solution to remove unreacted iron and impurities
- Pour the filtered solution into evaporating basin
- Heat the solution on hot plate at low to medium temperature
- Stir continuously with glass rod to prevent bumping
- Continue heating until crystallization begins at edges
- Remove from heat and allow to cool to room temperature
- Pour hot solution into beaker for crystallization
- Allow crystals to form as solution cools overnight
- Filter the crystals using filter paper and funnel
- Wash crystals with small amount of cold distilled water
- Dry crystals between folds of filter paper
Observation
Light green crystals formed during cooling. Crystals are uniform in size and shape. Solution becomes less concentrated as crystals separate. Crystals appear monoclinic in shape.
Result
Ferrous sulphate crystals successfully prepared. Yield approximately 60-70 percent. Crystals are pure and suitable for storage.
Precautions
- Do not heat solution excessively as decomposition may occur
- Stir continuously to prevent bumping during evaporation
- Allow proper cooling time for crystal formation
- Wash crystals with minimum water to prevent loss
- Ferrous sulphate oxidizes when exposed to air, keep in sealed container
- Handle iron filings carefully as they may rust
Viva Questions
What is the chemical formula of ferrous sulphate heptahydrate?
Ferrous sulphate heptahydrate has formula FeSO4.7H2O. It contains seven molecules of water of crystallization.
Why is ferrous sulphate solution greenish?
Ferrous sulphate solution appears greenish due to Fe2+ ions in solution. The color comes from the ferrous ion complex formation.
What happens when ferrous sulphate crystals are exposed to air for long time?
Ferrous sulphate oxidizes in air to ferric sulphate, changing color from light green to brownish-yellow due to formation of Fe3+ ions.
What is the purpose of filtration in this experiment?
Filtration removes unreacted iron filings and other insoluble impurities, giving a clear solution for crystallization.
Why do we cool the solution for crystallization?
Cooling decreases solubility of ferrous sulphate, causing it to crystallize out of solution. Pure crystals separate from mother liquor.
What is water of crystallization?
Water of crystallization is water chemically combined in crystal structure. Ferrous sulphate heptahydrate contains seven water molecules per formula unit.
More Class 10 Chemistry Practicals
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- To Find the pH of Samples Using Indicators
- To Study a Double Displacement (Precipitation) Reaction
- To Test Acids and Bases with Indicators
- To Verify the Law of Conservation of Mass
- To Study the Effect of Temperature on Reaction Rate
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