A sample of hard water contains 96 ppm of and 183 ppm of

CHEMISTRY · Multi-part · ICSE · Chemistry · Water · Water

Problem

A sample of hard water contains 96 ppm of

\text{SO}_4^{2-}

and 183 ppm of

\text{HCO}_3^-

, with

\text{Ca}^{2+}

as the only cation. (1) How many mole of

\text{CaO}

will be required to remove

\text{HCO}_3^-

from 1000 kg of this water? (2) If 1000 kg of this water is treated with the mass of

\text{CaO}

calculated above, what will be the concentration (in ppm) of residual

\text{Ca}^{2+}

ions (Assume

\text{CaCO}_3

to be completely insoluble in water)? (3) If the

\text{Ca}^{2+}

ions in one litre of the treated water are completely exchanged with hydrogen ions, what will be its pH (One ppm means one part of the substance in one million part of water, mass/mass)? (IIT May 1997)

Related theory

Stoichiometric Calculations
Compounds
Hard and soft water

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