Sodium Hydroxide, also known as lye, caustic soda and, incorrectly, according to IUPAC nomenclature, sodium hydrate, is a caustic metallic base. Sodium hydroxide forms a strong alkaline solution when dissolved in a solvent such as water. Pure sodium hydroxide is a white solid; commercially available in pellets, flakes, granules and as a 50% saturated solution. It is deliquescent 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.
Sodium hydroxide was traditionally used in soap making, known as cold process soap, saponification. A solution of sodium hydroxide in water was traditionally used as the most common paint stripper. Sodium hydroxide is frequently used as a cleaner, simply called "caustic" in such applications. It is added to water, heated, and then used to clean. It can dissolve oils and protein-based deposits. A sodium hydroxide soak solution is used as a powerful degreaser on stainless and glass ware. It is also the most common ingredient in oven cleaners.
Solid sodium hydroxide or solutions containing high concentrations of sodium hydroxide may cause chemical burns, permanent injury or scarring, and blindness. When dissolving sodium hydroxide in water, the reaction 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 that creates salts. For this reason, sodium hydroxide is very dangerous and skin should be washed thoroughly with water following contact with this substance. A solution of 0.5M or more of sodium hydroxide should be labeled corrosive, while a solution between 0.5-0.05M should be labeled irritant.
Sodium hydroxide can be used to make pigments: Chrome Green Lake is a mixture of chromium oxide with alumina; it is obtained by precipitating a solution of aluminum sulfate and a chromium salt by a soda solution. The precipitate, which contains aluminum and chromium hydroxides, on ignition takes a paler shade in proportion to the quantity of alumina it contains. For the chromium salt a solution of potassium bichromate, which has been allowed to stand with sulfuric acid and alcohol until it has acquired a pure green color, may be used. A Green Copper Lake can be made by adding copper sulfate solution, free from iron, to a hot decoction of yellow berries or weld until the liquid is emerald green, and then adding caustic soda solution in small quantities to precipitate the lake. The temperature of the liquid should not be more than 50° to 60° C. when the caustic soda is added. It has been maintained that these lakes turn out well only when the precipitation is so conducted that the residual liquid is quite colorless. It is probably advantageous to discontinue the addition of caustic soda when the liquid is somewhat colored, since when the precipitation is complete other substances besides the coloring matter may be precipitated.
|Typical Properties |
|Chemical Name: ||Sodium Hydroxide |
|Chemical Formula: ||NaOH |
|CAS No.: ||1310-73-2 |
|Mesh (%): ||Flakes |
|Color: ||White solid |
Keep in a tightly closed container, stored in a cool, dry, ventilated area. Protect against physical damage. Isolate from incompatible substances. Containers of this material may be hazardous when empty since they retain product residues (dust, solids); observe all warnings and precautions listed for the product.
Wear impervious protective clothing, including boots, gloves, apron or coveralls, as appropriate, to prevent skin contact. Use chemical safety goggles and/or full face shield where dusting or splashing of solutions is possible. Refer to Material Safety Data Sheet.
POISON! DANGER! CORROSIVE. MAY BE FATAL IF SWALLOWED. HARMFUL IF INHALED. CAUSES BURNS TO ANY AREA OF CONTACT. REACTS WITH WATER, ACIDS AND OTHER MATERIALS.
This product is toxic to aquatic organisms. If product is spilled, comply with Federal, State and local regulations on reporting spills. Refer to Material Safety Sheet and labels for further details.