JEE Advanced2010ChemistryHydrogenActual
The reagent(s) used for softening the temporary hardness of water is(are)
Options
- ACa ₃ ( PO ₄ )₂
- BCa ( OH )₂
- CNa ₂ CO ₃
- DNaOCl
Correct answer
B. Ca ( OH )₂
Step-by-step solution
Softening the temporary hardness of water means conversion of bicarbonate into calcium carbonate (precipitation) gathered Ca ( HCO ₃ )₂+ Ca ( OH )₂ 2 CaCO ₃ +2 H ₂ O Ca ( HCO ₃ )₂+ Na ₂ CO ₃ CaCO ₃ +2 NaHCO ₃ gathered Even NaOCl can be used, as in aqueous medium O Cl gets hydrolysed and makes solution alkaline enough to cause precipitation of CaCO ₃ . aligned NaOCl + H ₂ O & HOCl + NaOH OH ⁻+ HCO ₃⁻ & CO ₃²⁻+ H ₂ O aligned Representative elements (Hydrogen and its compounds) Conceptual II