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Water — CHEMISTRY STD 9 — Question

ICSE BoardEnglish MediumSTD 9CHEMISTRYWater3 Marks
Question
Explain with equation, what is noticed when permanent hard water is treated with Washing soda.
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Answer

When washing soda or soda ash is added to hard water, the corresponding insoluble carbonates settle down and can be removed by filtration.
$\mathrm{Ca}\left(\mathrm{HCO}_3\right)_2+\mathrm{Na}_2 \mathrm{CO}_3 \xrightarrow{\text { boil }} \mathrm{CaCO}_3 \downarrow+2 \mathrm{NaHCO}_3$ $\mathrm{Mg}\left(\mathrm{HCO}_3\right)_2+\mathrm{Na}_2 \mathrm{CO}_3 \xrightarrow{\text { boil }} \mathrm{MgCO}_3 \downarrow+2 \mathrm{NaHCO}_3$

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