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Acids, Bases and Salts — Science STD 10 — Question

CBSE BoardEnglish MediumSTD 10ScienceAcids, Bases and Salts3 Marks
Question
Name the compound whose one formula unit is associated with 10 water molecules. How is it prepared? Give equations of related reactions. Give two uses of the compound.
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Answer

The compound whose one formula unit is associated with 10 water molecules is sodium carbonate $\left( Na _2 CO _3 \cdot 10 H _2 O \right)$ commonly known as washing soda. It is prepared by heating baking soda and then recrystallizing the product so obtained.The equations related to the above reaction is:
$2\text{NaHCO}_3\xrightarrow{\ \Delta\ \ \ }\text{Na}_2\text{CO}_3\ +\ \text{H}_2\text{O}\ +\ \text{CO}_2$
$\text{Na}_2\text{CO}_3\ +\ 10\text{H}_2\text{O}\xrightarrow{\ \ \ \ \ \ \ \ \ }\text{Na}_2\text{CO}_3.10\text{H}_2\text{O}$
Two uses of washing soda are:
  1. It is used in glass, soap and paper industries.
  2. It is used for removing permanent hardness of water.

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