Question

Since there are $10$ water molecules in washing soda, hence it is known as:
(A) Sodium bicarbonate decahydrate
(B) Sodium carbonate decahydrate
(C) Sodium bicarbonate monohydrate
(D) Sodium decahydrate.

Answer 1

Hint: Washing soda is known as sodium carbonate and it has $10$ water molecules. $10$ is generally called deca as a prefix.

Complete step by step answer:
Washing soda is a white colored, odorless powder. Its chemical formula is $N{a_2}C{O_3}$ and is known as sodium carbonate. It is a moisture absorbing substance or what we can say as hygroscopic in nature. It is highly soluble in water and can form strong alkaline water solutions.
Preparation of washing soda:
The process of making washing soda is Solvay’s process includes reaction of sodium chloride, ammonia and carbon dioxide involved is produced through calcium carbonate and the left calcium oxide is used to recover ammonia from ammonium chloride.
At the beginning, sodium bicarbonate is obtained that is then converted to sodium carbonate on heating:
$NaCl + N{H_3} + C{O_2} + {H_2}O \to NaHC{O_3} + N{H_4}Cl$
$2NaHC{O_3} \to N{a_2}C{O_3} + {H_2}O + C{O_2}$
$N{a_2}C{O_3} + 10{H_2}O \to N{a_2}C{O_3} \cdot 10{H_2}O$
Finally, the washing soda is produced. As you can see that the ten molecules of water of crystallization are added to sodium bicarbonate. Therefore, it is known as sodium bicarbonate decahydrate.

So, the correct answer is “Option B”.


Note:
Washing soda is used in soap, glass and paper industries. Also, it can be used as a raw material in the manufacturing of various sodium compounds.Some use washing soda to make homemade laundry detergent, to clean especially in hard water, and some even use it as a laundry additive to soften water.