What is temporary hardness of water?

Question:

What is the temporary hardness of water?

Answer:

Temporary hardness of water refers to the presence of dissolved bicarbonate minerals, mainly calcium bicarbonate (Ca(HCO₃)₂) and magnesium bicarbonate (Mg(HCO₃)₂), which can be easily removed by boiling the water.

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What is Temporary Hardness?

• Definition: Temporary hardness is a type of water hardness caused by the presence of bicarbonate minerals.

• Common Minerals: The primary culprits are calcium bicarbonate (Ca(HCO3)2) and magnesium bicarbonate (Mg(HCO3)2).

Why is it Called “Temporary”?

• Temporary Reaction: When you heat water containing these bicarbonate minerals, a chemical reaction occurs, leading to the precipitation of insoluble carbonates.

• Result: The precipitates formed are calcium carbonate (CaCO3) and magnesium carbonate (MgCO3), which are not soluble in water and can be easily separated.

Boiling as a Solution

• Process: Boiling is a practical method to get rid of temporary hardness.

• How it Works: When water is heated, the bicarbonate ions present in temporary hardness react with heat to form carbonate ions and release carbon dioxide. This causes the formation of insoluble carbonates, which can be filtered out.

Chemical Equations

• Initial State: Ca(HCO3)2 or Mg(HCO3)2 in water.
• Boiling Reaction: Heat causes these bicarbonate ions to decompose.
  • Ca(HCO3)2 → CaCO3 + CO2 + H2O
  • Mg(HCO3)2 → MgCO3 + CO2 + H2O
• Result: Precipitation of calcium carbonate (CaCO3) or magnesium carbonate (MgCO3).

Importance for Indian Context

• Water Quality Concerns: In many parts of India, water sources exhibit temporary hardness due to high bicarbonate content.

• Domestic Impact: Understanding and addressing temporary hardness is crucial for improving the taste of water, reducing scale formation in appliances, and ensuring efficient soap usage.

Conclusion

Temporary hardness, characterized by the presence of bicarbonate minerals, is a common water quality issue. Boiling water is an effective method to remove temporary hardness, making it an accessible solution for areas facing this concern. Understanding and addressing water hardness are vital steps toward ensuring the availability of quality water for various domestic and industrial purposes.