Sodium hydroxide

Sodium hydroxide (NaOH) is an inorganic compound commonly known as lye or caustic soda. It is a white solid and highly soluble in water. Sodium hydroxide is a strong base, meaning it has a high pH value and can neutralize acids. Sodium hydroxide is widely used in many industries, including the manufacture of soaps, detergents, textiles, paper, and dyes, as well as for petroleum refining and water treatment. Sodium hydroxide is also used as a drain cleaner and in the process of refining biofuels. Handling sodium hydroxide requires care, as it is highly caustic and can cause chemical burns or other injury if not handled properly.


Sodium hydroxide (NaOH), also known as caustic soda, is a highly alkaline compound with the chemical formula NaOH.

Physical properties of sodium hydroxide:

  • Appearance: white crystalline solid
  • Odor: odorless
  • Solubility: soluble in water, slightly soluble in ethanol
  • Density: 2.13 g/cm3
  • Melting point: 318 °C (604 °F)
  • Boiling point: 1388 °C (2530 °F)

Chemical properties of sodium hydroxide:

  • Sodium hydroxide is a strong base and can react with acids to neutralize them, releasing heat in the process.
  • It can react with metals and metal compounds to form metal hydroxides.
  • Sodium hydroxide can react with carbon dioxide to form sodium carbonate.
  • Sodium hydroxide is highly reactive with organic compounds and can cause hydrolysis of esters, amides, and other compounds.
  • It is hygroscopic, which means it absorbs moisture from the air.


Sodium hydroxide (NaOH), also known as lye or caustic soda, is a highly caustic base and strong chemical base. Some of its major applications include:

  1. Soap making: Sodium hydroxide is used in the production of soap, either by saponification reaction with fats and oils, or by mixing with fatty acids to produce synthetic detergents.
  2. Paper production: Sodium hydroxide is used in the pulping process to make paper and cellulose products.
  3. Water treatment: Sodium hydroxide is used in water treatment to adjust the pH of water and to remove impurities such as heavy metals.
  4. Food industry: Sodium hydroxide is used as a food ingredient, most commonly in the production of olives, chocolate, and cocoa products.
  5. Oil refining: Sodium hydroxide is used in the refining of petroleum products to remove impurities.
  6. Drain cleaning: Sodium hydroxide is a common ingredient in drain cleaners as it reacts with and dissolves grease and other organic matter.
  7. Pharmaceuticals: Sodium hydroxide is used in the manufacture of certain pharmaceutical products, such as antacids and certain medications used for hypertension.


Sodium hydroxide is a strong and caustic base, and contact with the skin or eyes can cause chemical burns and potentially permanent damage. Protective equipment, such as gloves, clothing, and eye protection, should always be worn when handling sodium hydroxide or its solutions. In case of skin contact, rinse thoroughly with water for at least 10 to 15 minutes.

Dissolving sodium hydroxide is highly exothermic and can cause heat burns or ignite flammables. Additionally, it produces heat when reacted with acids. Sodium hydroxide is also mildly corrosive to glass and can corrode certain metals, such as aluminum, which can produce flammable hydrogen gas.

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