What is Sodium Hydroxide

Sodium hydroxide is an alkaline BASE, its pH (A scale used to measure the acidity or alkalinity of a substance. It ranges from 0 to 14, with pH’s below seven being acidic and greater than 7 being basic. A pH of 7 is neutral) value is 14. It has multiple names say LYE and caustic soda. The properties of the chemical make it ideal for use in a number of different applications, mainly used in the manufacturing of Paper, textiles, soaps etc. It is a chemical compound with a high alkaline content.

Properties: Lye as some may call it has NO ODOR and can be solid or liquid. In its PURE form sodium hydroxide is in the form of WHITE SOLID pellets or flakes.  It contains sodium cations and hydroxide anions. It reacts with WATER (H2O) to give the same, the chemical reaction is as follows:-

                                                            NaOH + H2O → Na+ + OH- +H20

When dissolved in water or neutralized with acid it liberates substantial heat, which may be sufficient to ignite combustible materials. Sodium hydroxide is very corrosive in nature.

The boiling point and melting point of NaOH are 1388 °C, 1661 K, 2530 °F; 318 °C, 591 K, 604 °F respectively.

It is Caustic in nature i.e. can damage HUMAN TISSUES.

The pure form of Sodium hydroxide continuously absorbs carbon dioxide from air I.E. CO2, making it necessary to keep the compound in an air tight container.

Sodium hydroxide is used to manufacture soaps, rayon, paper, explosives, dyestuffs, and petroleum products. It is also used in processing cotton fabric, laundering and bleaching, metal cleaning and processing, oxide coating, electroplating, and electrolytic extracting. It is commonly present in commercial drain and oven cleaners.

Production: In Industries NaOH is produced electrolytically, by passing an electric current through a Sodium Chloride Solution.

Diaphragm cell process: In this process NaOH is prepared by  using a special membrane, NaOH solution is allowed to exit the cell and be collected while the other products remain behind. This setup basically has two graphite anodes in a NaCl solution surrounded by a wire screen cathode with an asbestos diaphragm in between. NaOH is produced at the cathode and drips out of the cell while the Cl2 gas bubbles out without reacting with the water. This is called a “diaphragm cell”. The reaction is as follows:

2 Na+Cl– + 2 H2O + 2 e– → H2 + 2 Cl– + 2 NaOH

Mercury Cell Process: Another process, called a “Mercury Cell”, Hg (mercury) serves as the cathode, which reduced Na+ ions to Na metal which then dissolves in the Hg. The Hg-Na amalgam is then exposed to pure water (not NaCl solution) and the Na will react to produce NaOH and H2 gas. This procedure is supposed to produce much purer NaOH.


Applications of NaOH: Due to its strong BASIC nature, NaOH is used in many ways. Basically used where we require to increase the alkalinity of a mixture, or to neutralize acids.

  • Used In paper Industry to make paper. NaOH is a key component of the white liquor to separate lignin from cellulose and also used for BLEACHING later in paper making process.
  • Cleansing agent: Used in industries for cleansing of various containers etc.
  • Domestic USES: Used in our homes as a cleansing agent, we can find ourselves surrounded with such products be it a DRAIN cleaner a DISH washer.

*One must keep in mind that NaOH is a highly alkaline base and can damage our EYES and TISSUES upon exposure so one must handle it with extreme care.