Washing soda exists as a decahydrate, . When it is exposed to dry air at room temperature, it underg — s Block Elements Chemistry Question

💡 Solution & Explanation

Efflorescence is the spontaneous loss of water of crystallization. When exposed to air, $Na_2CO_3 \cdot 10H_2O$ loses 9 molecules of water and crumbles to a white powder, forming the stable monohydrate ($Na_2CO_3 \cdot H_2O$). Heating above 373 K is required to form anhydrous soda ash.