How is Sodium Sulphate Prepared by Titration Method?

Sodium sulfate is prepared by titration by carefully neutralizing sodium hydroxide with sulfuric acid, then evaporating the solution to obtain crystals.

Here's a breakdown of the process:

Titration Process for Sodium Sulfate Production

This method relies on a classic acid-base neutralization reaction:

• Reactants: The two key ingredients are:
  • Sodium hydroxide (NaOH): This is a strong base, measured and placed into a flask.
  • Sulfuric acid (H₂SO₄): This is a strong acid that will be added carefully during titration.
• Titration: The process involves the following steps:
  1. Preparation: A known quantity of sodium hydroxide is placed in a flask.
  2. Titration: Sulfuric acid is slowly added to the sodium hydroxide solution while stirring continuously.
  3. Neutralization: The process continues until the solution is neutralized, meaning there is no excess of either acid or base. This can be confirmed using an indicator, like phenolphthalein, that changes color at a specific pH.
  4. Evaporation: After the titration is complete, the neutralized solution is evaporated by applying heat on a Bunsen burner until the water has evaporated. The remaining solution is transferred to a crystallizing dish.
• Crystallization: The final solution is allowed to cool and evaporate slowly, leading to the formation of sodium sulfate (Na₂SO₄) crystals.

Detailed Steps

The preparation process follows a step-by-step approach:

1. Measurement: A specific quantity of sodium hydroxide is accurately measured, and placed in the flask for the titration process.
2. Sulfuric Acid Addition: Sulfuric acid is carefully added to the sodium hydroxide solution using a burette. This gradual addition is crucial for a precise reaction.
3. Reaction: The sulfuric acid neutralizes the sodium hydroxide, forming sodium sulfate and water:
   • 2NaOH + H₂SO₄ → Na₂SO₄ + 2H₂O
4. Endpoint Detection: The point at which the solution is completely neutralized is known as the equivalence point. An indicator can be used to determine this point.
5. Evaporation: The solution is then heated to evaporate the water, leaving behind sodium sulfate.
6. Crystallization: The hot saturated solution is poured into a crystallizing dish and allowed to cool down slowly, forming sodium sulfate crystals.

Key Points:

• The reaction is carried out slowly to ensure a complete neutralization.
• Precise measurements of reactants are essential for accurate results.
• The solution must be evaporated gently to prevent spattering.