What happens when solid sodium hydroxide is exposed to air
When solid sodium hydroxide (NaOH) is exposed to air, it readily absorbs moisture from the air, causing it to dissolve and form a highly corrosive and caustic solution. This absorption of moisture is known as deliquescence. Sodium hydroxide is hygroscopic, meaning it attracts and holds water molecules from the surrounding environment. As a result, the solid sodium hydroxide forms a concentrated and corrosive solution of sodium hydroxide, commonly known as caustic soda.
The reaction with moisture is exothermic, meaning it releases heat. So, when solid sodium hydroxide comes into contact with air, it not only dissolves but also generates heat. This property further enhances its deliquescence, as the generated heat accelerates the absorption of moisture, resulting in the formation of a concentrated sodium hydroxide solution.
It is important to handle solid sodium hydroxide with care as it is highly caustic and can cause severe chemical burns on contact with skin or eyes. When exposed to air, it should be stored in tightly sealed containers or kept in a controlled environment with low humidity to prevent its deliquescence and the formation of a corrosive solution.