| Compound name | Potassium Hydroxide |
| Compound type | Inorganic |
| Synonyms | Caustic potash |
| Linear formula | KOH |
| Molar mass | 56.11 g/ml |
| Molecular Weight | 56.11 |
| Solubility in water | 1.12 g/ml at 20°C, exothermic reaction |
| Appearance | White solid |
| Interaction with atmospheric water vapours | Hygroscopic, Deliquescence |
| Solubility | Soluble in alcohol, glycerol insoluble in ether, liquid ammonia |
| CAS Number | 1310-58-3 |
| EC Number | 215-181-3 |
| PubChem Substance ID | 329766684 |
| MDL number | MFCD00003553 |
| NACRES | NA.23 |
| SMILES string | [OH-].[K+] |
| InChI | 1S/K.H2O/h;1H2/q+1;/p-1 |
| InChI key | KWYUFKZDYYNOTN-UHFFFAOYSA-M |
| Remarks | Dangerously corrosive |
- Potassium hydroxide (chemical formula KOH), also known as caustic potash, is a strong alkaline compound composed of potassium (K⁺) and hydroxide (OH⁻) ions. It typically appears as white or colorless solid flakes, pellets, or powders, and is highly hygroscopic, meaning it readily absorbs moisture and carbon dioxide from the atmosphere.
- When dissolved in water, potassium hydroxide produces a strongly basic solution with a high pH, releasing substantial heat in an exothermic reaction. This makes it one of the most powerful and widely used alkalis in both laboratory and industrial settings.
- In industry, potassium hydroxide is a critical chemical reagent used in the manufacture of numerous products. It is employed in the production of potassium carbonate, potassium phosphates, liquid fertilizers, dyes, soaps, detergents, biodiesel, alkaline batteries, and certain pharmaceuticals. In soap making (saponification), KOH reacts with fats and oils to produce soft or liquid soaps, which are more soluble than their sodium-based counterparts. Its strong alkalinity and ability to break down organic materials also make it effective in cleaning agents and drain openers.
- In the chemical industry, potassium hydroxide is used as a strong base in organic synthesis and analytical chemistry. It serves as a catalyst, pH regulator, and neutralizing agent, and plays a vital role in the production of biodiesel, where it catalyzes the transesterification of triglycerides into methyl or ethyl esters. It is also a key component in alkaline batteries (such as nickel-cadmium and nickel-metal hydride batteries), where it functions as the electrolyte due to its excellent ionic conductivity and stability.
- In agriculture, potassium hydroxide is used in the preparation of liquid potassium fertilizers and in the treatment of acidic soils. Its ability to solubilize plant nutrients makes it a valuable tool in precision farming and hydroponic systems. It is also used in food processing, albeit in highly regulated quantities. As a food additive (designated E525), it serves as a pH stabilizer, thickener, or peeling agent, particularly in products like cocoa, soft drinks, and olives.
- In medicine and diagnostics, potassium hydroxide is used in KOH preparations, a diagnostic test in dermatology and microbiology for detecting fungal elements in skin, hair, or nail samples. The KOH dissolves keratin and other debris, allowing clearer microscopic visualization of fungal hyphae or spores.
- Despite its versatility, potassium hydroxide is highly caustic and corrosive, posing serious risks upon contact with skin, eyes, or mucous membranes. Inhalation of dust or mist can irritate the respiratory tract, while ingestion can result in severe burns to the esophagus and stomach. Therefore, its handling requires strict safety precautions, including personal protective equipment and proper ventilation. Environmentally, KOH is not persistent and neutralizes easily, but its high alkalinity can cause local damage to aquatic life if released in large quantities.
