Verified Solution • 2025–26 Session moderate

QJEEM22Che33f: JEE Main 2022 Chemistry - Class 11 JEEM22Che33f Solution: The metal salts formed during softening of hardwater using…

The metal salts formed during softening of hardwater using Clark's method are :

Multiple Choice Options

  • A Ca(OH)2\mathrm{Ca}(\mathrm{OH})_{2} and Mg(OH)2\mathrm{Mg}(\mathrm{OH})_{2}
  • B CaCO3\mathrm{CaCO}_{3} and Mg(OH)2\mathrm{Mg}(\mathrm{OH})_{2}
  • C Ca(OH)2\mathrm{Ca}(\mathrm{OH})_{2} and MgCO3\mathrm{MgCO}_{3}
  • D CaCO3\mathrm{CaCO}_{3} and MgCO3\mathrm{MgCO}_{3}

Step-by-Step Verified Solution

In Clark's method, calculated amount of lime is added to hard water. It precipitates out calcium carbonate and magnesium hydroxide which can filtered off.

amp;Ca(HCO3)2+Ca(OH)2→2CaCO3↓+2H2Oamp;Mg(HCO3)2+2Ca(OH)2→2CaCO3↓+Mg(OH)2+2H2O\begin{aligned}&\mathrm{Ca}\left(\mathrm{HCO}_{3}\right)_{2}+\mathrm{Ca}(\mathrm{OH})_{2} \rightarrow 2 \mathrm{CaCO}_{3} \downarrow+2 \mathrm{H}_{2} \mathrm{O} \\\\&\mathrm{Mg}\left(\mathrm{HCO}_{3}\right)_{2}+2 \mathrm{Ca}(\mathrm{OH})_{2} \rightarrow 2 \mathrm{CaCO}_{3} \downarrow+\mathrm{Mg}(\mathrm{OH})_{2}+2 \mathrm{H}_{2} \mathrm{O}\end{aligned}

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