Which method is used to remove temporary hardness of water?

Question:

Which method is used to remove the temporary hardness of water?

Answer:

• The most effective method to remove temporary hardness from water is boiling.
• Also, Clark’s method is used to remove the temporary hardness of water.

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👉 Also, Explore All Important Questions and Answers on Chemistry

Boiling as a Practical Solution

• Why Boiling? Boiling water is a simple and efficient method to eliminate temporary hardness.

• Heat-Induced Reaction: When water is heated, the bicarbonate minerals responsible for temporary hardness undergo a chemical change.

The Boiling Process

• Step 1: Water containing calcium bicarbonate (Ca(HCO3)2) or magnesium bicarbonate (Mg(HCO3)2).

• Step 2: Application of heat through boiling.

• Step 3: Chemical Reaction: Bicarbonate ions decompose, leading to the formation of insoluble carbonates.

• Result: Precipitation of calcium carbonate (CaCO3) or magnesium carbonate (MgCO3).

Chemical Equations

• Initial State: Ca(HCO3)2 or Mg(HCO3)2 in water.
• Boiling Reaction:
  • Ca(HCO3)2 → CaCO3 + CO2 + H2O
  • Mg(HCO3)2 → MgCO3 + CO2 + H2O

• Formation of Precipitates: Calcium carbonate (CaCO3) or magnesium carbonate (MgCO3) precipitates and settles.

Separation of Precipitates

• Filtration: After boiling, the water is filtered to remove the formed calcium carbonate or magnesium carbonate.

• Result: The filtered water is now free from the bicarbonate minerals causing temporary hardness.

Clark’s Method for Removing Temporary Hardness of Water

• Clark’s method is an alternative approach to tackle the issue of temporary hardness in water. Developed by British chemist Thomas Clark, this method involves the addition of calcium hydroxide (lime) to hard water.

• The added lime reacts with the bicarbonate ions present in temporary hardness, leading to the formation of insoluble calcium carbonate.

• This calcium carbonate precipitates and can be easily separated through settling or filtration. The chemical equation for the reaction is:

Ca(OH)₂ + 2HCO^3⁻ → CaCO₃ + 2H₂O + CO₂.

• Clark’s method is particularly useful for large-scale water treatment processes and is employed in water treatment plants to enhance water quality by mitigating temporary hardness.

• However, it’s essential to carefully control the amount of lime added to avoid over-alkalinity. Clark’s method offers an additional option for regions seeking effective solutions to improve the taste and usability of water afflicted with temporary hardness.

Benefits

• Accessible Solution: Boiling is a widely available and affordable method, making it suitable for regions facing temporary hardness issues.

• Improving Water Quality: By removing temporary hardness, the taste of water improves, and issues like scale formation in appliances are reduced.

Practical Considerations

• Household Application: Boiling is practical for domestic use, especially in areas with limited access to advanced water treatment technologies.

• Energy Considerations: While boiling is effective, it’s important to consider the energy required for large-scale applications.

Conclusion

Boiling water is a straightforward and effective method for removing temporary hardness. This practical solution is particularly valuable for households in India and other regions facing issues related to the taste and quality of water due to temporary hardness. Understanding and implementing such methods contribute to ensuring access to clean and palatable water for various purposes.