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Why is sodium hydroxide called caustic soda?
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Sodium hydroxide (NaOH) is called caustic soda because it is a strong, corrosive alkali that is highly destructive to organic tissues.123
The term "caustic" refers to any substance capable of burning or destroying animal or vegetable tissue through chemical action. Because sodium hydroxide is a powerful base, it is classified as a caustic agent. The name "soda" is historically associated with sodium-bearing compounds, and in industrial contexts, sodium hydroxide is distinguished from other alkalies like soda ash (sodium carbonate) by its intense, corrosive properties.123