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What do you observe when washing soda is exposed to air?

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Hint: Sodium carbonate, also known as washing soda, soda ash, and soda crystals, is an inorganic compound with the formula \[N{a_2}C{O_3}\]. These are all white water soluble salts that provide a mildly alkaline water solution.

Complete answer:
The chemical formula for washing soda is \[N{a_2}C{O_3}.10{H_2}O.\]
As a result, when we expose washing soda to sunlight, it quickly loses its crystallisation water.
It will turn into white powder as a result. As a result, efflorescence refers to the whole phase of water crystallisation being lost by washing soda when exposed to air.
This process' chemical reaction equation is as follows.
\[\]\[N{a_2}C{O_3}.10{H_2}O\, \to N{a_2}C{O_3}.{H_2}O + 9{H_2}O\]
Crystals of washing soda are efflorescent. When exposed to the atmosphere, efflorescent substances lose their water of crystallisation. As a result, when washing soda crystals are exposed to air, they lose their crystallisation water and become amorphous.
We can see that washing soda loses 9 molecules of water during the crystallisation process in the above reaction. Efflorescence refers to the method of removing crystallisation water. It can also be described as the process of a hydrate losing water or hydration. Actually it is said to be, Sodium carbonate decahydrate loses nine molecules of water to form Sodium carbonate monohydrate, as in this case.
An efflorescent material is one that loses moisture when it is exposed to the air. The moisture present in the form of water molecules in compounds is referred to as water of crystallisation. A compound's crystalline form is determined by the presence of these water molecules.

Note:
Washing powder is blue in crystalline form due to the presence of water molecules, but becomes white when exposed to the atmosphere due to the lack of water molecules.
Hygroscopic is the polar opposite of efflorescent. A hygroscopic material is one that absorbs moisture from the environment without being dissolved in it.
Hygroscopicity is a property of dry washing powder. As washing soda powder is exposed to the elements, it absorbs water molecules from the air and recrystallizes as sodium carbonate decahydrate. To avoid contact with the air, it is recommended that washing powder be stored in airtight containers.