Potassium hydroxide
Encyclopedia : P : PO : POT : Potassium hydroxide
| Potassium hydroxide | |
|---|---|
| |
| General | |
| Other names | Potash lye |
| Molecular formula | KOH |
| Molar mass | 56.11 g/mol |
| Appearance | white solid, deliquescent |
| CAS number | [1310-58-3] |
| Properties | |
| Density and phase | 2.044 g/cm3, solid |
| Solubility in water | 1100 g/L (25 °C) |
| Melting point | 406 °C |
| Boiling point | 134 °C |
| Vapour Pressure | 1.3hPa (719 ° C) |
| Basicity (pKb) | 0 |
| Structure | |
| Coordination geometry | ? |
| Crystal structure | ? |
| Hazards | |
| MSDS | External MSDS |
| EU classification | Corrosive (C) |
| NFPA 704 | |
| R-phrases | R22, R35 |
| S-phrases | S1/2, S26, S36/37/39, S45 |
| Flash point | non flammable |
| RTECS number | TT2100000 |
| Supplementary data page | |
| Structure and properties | n, εr, etc. |
| Thermodynamic data | Phase behaviour Solid, liquid, gas |
| Spectral data | UV, IR, NMR, MS |
| Related compounds | |
| Other anions | Potassium oxide Potassium peroxide Potassium superoxide |
| Other cations | Lithium hydroxide Sodium hydroxide Rubidium hydroxide Caesium hydroxide |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) [Chemical infoboxInfobox disclaimer and references] | |
The chemical compound potassium hydroxide, (KOH) sometimes known as caustic potash, potassa, potash lye, and potassium hydrate, is a metallic base. It is a very alkaline compound used in agriculture to correct the pH of acidic soils. It can also be used as a fungicide or even an herbicide.
Uses
It is a major industrial chemical used as a base in a wide variety of chemical processes. It is used as a catalyst in reactions like the production of biodiesel by transesterification. Advantages of using potassium hydroxide (KOH) and not sodium hydroxide (NaOH) in biodiesel production include: NaOH "clumps" and KOH does not, KOH dissolves faster in methanol, the resulting glycerin is thinner using KOH and therefore less likely to plug up the plumbing and pumps, and the glycerin is more biodegradable so it's better for composting.Some uses of KOH include acrylate ester copolymer coating, defoaming agents used in the manufacture of paper, formulation aid for food, pH control agent, polyethylene resins, textile processing.
Other uses include in veterinary medicine in disbudding calves horns and to dissolve scales and hair; in human medicine, to diagnose fungal infections and as a wart and cuticle solvent; manufacture of cleansers. This type of compound is also used in washing powders, some denture cleaners, non-phosphate detergents, and drain or pipe cleaners.
A very significant use of KOH in terms of significance to the average person is that alkaline batteries use an aqueous solution of KOH as an electrolyte. Thus, potassium hydroxide helps to power flashlights, smoke detectors, and other battery powered household items.
It is also an anisotropic etchant of silicon, exposing octahedral planes. This technique can create pyramyds and regularly-shaped etch pits for uses such as MEMS.
Food preparation
Food uses of lye include washing or chemical peeling of fruits and vegetables, chocolate and cocoa processing, caramel color production, poultry scalding, soft drink processing, and thickening ice cream. Olives are often soaked in lye to soften them, while pretzels and German lye rolls are glazed with a lye solution before baking to make them crisp.Lye is used to make the Scandinavian delicacy known as lutefisk (from lutfisk, "lye fish"). Cod is soaked in lye to a jelly-like consistency, then served with bacon fat, potatoes, brunost sauce and mushy peas. Hominy is dried maize (corn) kernels reconstituted by soaking in lye
See also
External links
- For a full list of external links to MSDSs, spectroscopic data, commercial chemicals suppliers etc. for this compound, see [Chemical sources].
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