Sodium hydroxide
[CAS# 1310-73-2]

Identification

• Classification: Inorganic chemical industry >> Inorganic base
• Name: Sodium hydroxide
• Synonyms: Caustic soda
• Molecular Formula: NaOH
• Molecular Weight: 40.00
• CAS Registry Number: 1310-73-2
• EC Number: 215-185-5
• SMILES: [OH-].[Na+]

Properties

• Density: 2.13
• Melting point: 318 °C
• Boiling point: 1390 °C
• Decomposition: 176-178 °C
• Water solubility: SOLUBLE

Safety Data

• Hazard Symbols: GHS05;GHS07 Danger
• Risk Statements: H290-H314-H315-H318-H319
• Safety Statements: P234-P260-P264-P264+P265-P280-P301+P330+P331-P302+P352-P302+P361+P354-P304+P340-P305+P351+P338-P305+P354+P338-P316-P317-P321-P332+P317-P337+P317-P362+P364-P363-P390-P405-P406-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin corrosion	Skin Corr.	1A	H314
Substances or mixtures corrosive to metals	Met. Corr.	1	H290
Serious eye damage	Eye Dam.	1	H318
Specific target organ toxicity - single exposure	STOT SE	3	H335
Acute toxicity	Acute Tox.	4	H312
Eye irritation	Eye Irrit.	2	H319
Chronic hazardous to the aquatic environment	Aquatic Chronic	3	H412
Specific target organ toxicity - single exposure	STOT SE	1	H370
Acute toxicity	Acute Tox.	4	H302
Skin corrosion	Skin Corr.	1C	H314
Skin corrosion	Skin Corr.	1	H314
Acute hazardous to the aquatic environment	Aquatic Acute	3	H402

• Transport Information: UN 1823

Discovery and Applications

Sodium hydroxide (NaOH), commonly known as caustic soda or lye, is an important industrial chemical that was first isolated by Sir Humphry Davy in 1807. He discovered it through the electrolysis of sodium carbonate, a process that also led to the discovery of sodium metal. Davy's research on sodium hydroxide established its role as an essential base in a variety of chemical reactions and industrial processes.

Sodium hydroxide is a white solid base that is highly corrosive. It is highly soluble in water, forming a strongly alkaline solution with a pH of approximately 14. The compound has a melting point of 318°C and is hygroscopic, meaning it readily absorbs moisture from the air. This property makes it essential in applications that require precise control of pH.

Sodium hydroxide is widely used in industrial settings. It is a key reagent in the production of a variety of chemicals, including sodium carbonate (soda ash), sodium hypochlorite (bleach), and sodium phosphate. These chemicals are the basis of many industrial processes. NaOH is used in the kraft paper process for pulping wood to help dissolve lignin and separate it from cellulose fibers, resulting in a high-quality paper product.

In water treatment, sodium hydroxide performs a variety of functions and is used to neutralize acidic water and adjust pH to ensure safe and effective treatment. This helps prevent corrosion in water supply systems and maintains the effectiveness of water purification processes. NaOH is used to remove hardness from water by precipitating calcium and magnesium ions, which reduces scale formation and improves water quality.

Sodium hydroxide has an important use in food processing. It is used in a variety of food processing applications, including the production of foods such as pretzels and olives. NaOH helps achieve the desired texture and color by neutralizing acidic substances and enhancing certain properties of foods. It is an ingredient in many detergents used in food production facilities because of its ability to dissolve grease and remove organic matter.

NaOH is essential in the production of soaps and detergents. It is used in the saponification process, where fats and oils are converted to soap and glycerin. Sodium hydroxide reacts with fatty acids to form the sodium salts of fatty acids, which are the active detergents in soaps. In detergents, NaOH helps adjust pH and improves the effectiveness of surfactants used for cleaning.

In the laboratory, sodium hydroxide is a valuable reagent. It is used in titrations and various chemical reactions to provide a precise basis for reaction conditions. Its strong alkalinity makes it ideal for neutralizing acids and performing analytical procedures. NaOH is used to synthesize compounds and study reaction mechanisms.

Because sodium hydroxide is corrosive, it must be handled with care, wearing appropriate protective gear including gloves, goggles, and a lab coat, and avoiding contact with skin and eyes. Inhalation of dust or fumes should be avoided. Store NaOH in a closed container in a cool, dry place away from moisture and acids. Ensure that the area of ​​use is well ventilated to prevent the accumulation of harmful fumes.

The impact of sodium hydroxide on the environment is manageable as long as proper precautions are taken. It is not biodegradable, but is neutralized in the environment by reacting with acids to form salts and water. Control measures should be in place to prevent accidental spills and releases, as high concentrations can be harmful to aquatic ecosystems and soil.

References

1979. Treatment of cereal straw with sodium hydroxide solution. Effect of treatment of cereal straw sodium hydroxide solution on the amount and place of digestion of starch and crude cellulose by dairy cows. Archiv fur Tierernahrung, 29(2).
DOI: 10.1080/17450397909424609

1979. Removal of deleterious glucosides from safflower meal. Journal of the American Oil Chemists’ Society, 56(5).
DOI: 10.1007/bf02660234

2000. Preparation of Monoclonal Antibodies Using Ion Exchange Chromatography. Diagnostic and Therapeutic Antibodies.
DOI: 10.1385/1-59259-076-4_289