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When washing soda is exposed to hot atmosphere for a long time, it:
gains water molecules and dissolves in them
gains heat from the Sun and becomes dry
loses water molecules and becomes powdery
loses water molecules but remains in crystal form
loses water molecules and becomes powdery
Washing soda is chemically known as sodium carbonate decahydrate (Na2тАЛCO3тАЛтЛЕ10H2тАЛO). When exposed to air or heat, it undergoes a process called efflorescence, where it loses its water of crystallization and turns into a white, powdery anhydrous form.
Washing soda is chemically known as sodium carbonate decahydrate (Na2тАЛCO3тАЛтЛЕ10H2тАЛO). When exposed to air or heat, it undergoes a process called efflorescence, where it loses its water of crystallization and turns into a white, powdery anhydrous form.
Think of a fresh sponge that holds water; when you leave it out in the hot sun for a long time, the water evaporates, leaving the sponge dry and shriveled rather than plump and hydrated.
W.A.P: Washing soda, Anhydrous, Powder.
Na2тАЛCO3тАЛтЛЕ10H2тАЛO тАФ Formula for hydrated sodium carbonate (washing soda)
Na2тАЛCO3тАЛ тАФ Formula for anhydrous sodium carbonate (soda ash)
The process is driven by the vapor pressure of the hydrated salt being higher than the partial pressure of water vapor in the atmosphere. The chemical reaction is: Na2тАЛCO3тАЛтЛЕ10H2тАЛO(s)╬ФтАЛNa2тАЛCO3тАЛ(s)+10H2тАЛO(g). Upon losing the 10 water molecules, the clear crystalline structure collapses into a fine, white amorphous powder known as soda ash.
The process of losing water of crystallization upon exposure to air is called efflorescence.
Washing soda contains 10 molecules of water of crystallization per formula unit.
The powdery substance formed is anhydrous sodium carbonate.
Manufacturing of glass, soap, and paper
Softening of hard water
Hydrated crystals that lose water to the atmosphere are described as efflorescent.
Option A is incorrect because washing soda loses water, not gains it. Option B is partially true regarding drying but fails to mention the structural change to powder. Option D is incorrect because the crystalline lattice structure is destroyed upon dehydration.
C is correct тАФ washing soda undergoes efflorescence, losing its water of crystallization to become a white, powdery anhydrous salt.
Remember that efflorescence is the opposite of deliquescence; while washing soda loses water to the air, substances like NaOH (deliquescent) absorb water from the air to dissolve.
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