Product name : Sodium Hydroxide

Other names : Caustic soda;Lye ;sodium hydroxide solid; sodium hydrate

CAS # :  1310-73-2

Items                                    Properties
Molecular formula              NaOH
Molar mass                         39.9971 g/mol
Appearance                        white solid,hygroscopic
Density                                 2.13 g/cm3
Melting point                        323 °C, 596 K, 613 °F
Boiling point                        1388 °C, 1661 K, 2530 °F
Solubility in water               111 g/100 ml (20 °C)
Solubility in ethanol           13.9 g/100 mL
Solubility in methanol       23.8 g/100 mL
Solubility in glycerol           soluble
Refractive index (nD)         1.412
pH                                         13 - 14 (0.5% soln.)

Characteristics and Application :

Sodium hydroxide (NaOH), also known as lye and caustic soda, is a caustic metallic base. Sodium hydroxide forms a strong alkaline solution when dissolved in a solvent such as water, however, only the hydroxide ion is basic. It is used in many industries, mostly as a strong chemical base in the manufacture of pulp and paper, textiles, drinking water, soaps and detergents and as a drain cleaner.

Pure sodium hydroxide is a white solid; available in pellets, flakes, granules and as a 50% saturated solution. It is hygroscopic and readily absorbs carbon dioxide from the air, so it should be stored in an airtight container. It is very soluble in water with liberation of heat. It also dissolves in ethanol and methanol, though it exhibits lower solubility in these solvents than potassium hydroxide. It is insoluble in ether and other non-polar solvents. A sodium hydroxide solution will leave a yellow stain on fabric and paper.

Uses :

Sodium hydroxide was traditionally used in soap making (cold process soap, saponification).

Sodium hydroxide is used in the home as a drain cleaning agent for clearing clogged drains. It is distributed as a dry crystal or as a thick liquid gel. The chemical mechanism employed is the conversion of grease to a form of soap. Soap is water-soluble, and can be dissolved by flushing with water. Sodium hydroxide also decomposes complex molecules such as the protein that composes hair. Such drain cleaners (and their acidic versions) are highly caustic and should be handled with care.

Sodium hydroxide has been used as a relaxer to straighten hair. However, because of the high incidence and intensity of chemical burns, chemical relaxer manufacturers have now switched to other alkaline chemicals, although sodium hydroxide relaxers are still available, used mostly by professionals.

Safety :

Solid sodium hydroxide or solutions of sodium hydroxide will cause chemical burns, permanent injury or scarring, and blindness if it contacts unprotected human or animal tissue. Protective equipment such as rubber gloves, safety clothing and eye protection should always be used when handling the material or its solutions.

Dissolution of sodium hydroxide is highly exothermic, and the resulting heat may cause heat burns or ignite flammables.

Sodium hydroxide is extremely caustic, and can react with fats and oils on skin, in a reaction which creates salts. For this reason, sodium hydroxide is very dangerous, and skin should immediately be rinsed with mild acid, such as vinegar or low molar citric acid, following exposure. Do NOT wash with water following contact with this substance as this will merely exacerbate the corrosive affect.