The Amazing Properties and Uses of Sodium
Hydroxide

Sodium
Hydroxide, also known as lye or caustic soda, is an inorganic compound with the
chemical formula NaOH. It is a highly caustic metallic base and alkali salt
that forms a strongly alkaline solution in water. Caustic soda occurs as a
deliquescent white solid that readily absorbs moisture from air to form a
strongly alkaline solution.



Physical and Chemical Properties



Caustic soda has a molecular formula of NaOH and a relative molecular mass of 40.00
g/mol. It exists as odorless white crystals or as white opaque pellets at room
temperature. Caustic soda is very soluble in water and forms a highly alkaline
caustic soda solution that turns red litmus blue. The saturated aqueous
solution of caustic soda is referred to as lye and has pH of approximately
13.15. Caustic soda is stable in dry air but absorbs moisture and carbon
dioxide when exposed to humid air, forming a white precipitate layer on its
surface. It has a melting point of 318°C and decomposes when heated to higher
temperatures. Caustic soda reacts vigorously with many acids, generating heat
and evolving hydrogen gas.



Production of Caustic soda



The Sodium
Hydroxide  main industrial
production method for caustic soda involves the electrolysis of a concentrated
sodium chloride solution. In this process, known as the chloralkali process,
sodium chloride (NaCl) solution is electrolyzed in a cell containing a
diaphragm and electrodes. Oxygen gas is produced and removed at the anode while
chlorine gas is generated at the cathode. Caustic soda is then produced as an
aqueous solution at the cathode. Some caustic soda is also produced from the
reaction of soda ash (sodium carbonate) with calcium hydroxide in the Mannheim
process.

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