Question
Download Solution PDFTemporary hardness in water is due to which one of the following of Calcium and Magnesium?
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFThe correct answer is Hydrogen Carbonates.
Key Points
- Temporary hardness is due to the presence of Calcium hydrogen carbonate Ca(HCO3)2(aq) and Magnesium hydrogen carbonate Mg(HCO3)2(aq).
- The hydrogen carbonates of both Calcium and Magnesium decompose upon heating.
- The original insoluble carbonate is reformed when water is boiled.
- The following is the precipitation reaction -
- Ca(HCO3)2(aq) → CO2(g) + H2O(l) + CaCO3
- Mg(HCO3)2(aq)→CO2(g) + H2O(l) + MgCO3
- Boiling of water results in the removal of Magnesium and Calcium ions from water, and thus its hardness.
- This is the reason why it is called temporary hardness.
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