Potassium hydroxide is an inorganic compound with the formula KOH, and is commonly called caustic potash. Along with sodium hydroxide (NaOH), KOH is a prototypical strong base. It has many industrial and niche applications, most of which exploit its caustic nature and its reactivity toward acids. An estimated 700,000 to 800,000 tonnes were produced in 2005. KOH is noteworthy as the precursor to most soft and liquid soaps, as well as numerous potassium-containing chemicals. It is a white solid that is dangerously corrosive. KOH exhibits high thermal stability. Because of this high stability and relatively low melting point, it is often melt-cast as pellets or rods, forms that have low surface area and convenient handling properties. These pellets become tacky in air because KOH is hygroscopic. Most commercial samples are ca. 90% pure, the remainder being water and carbonates. Its dissolution in water is strongly exothermic. Concentrated aqueous solutions are sometimes called potassium lyes. Even at high temperatures, solid KOH does not dehydrate readily. At higher temperatures, solid KOH crystallizes in the NaCl crystal structure. The group is either rapidly or randomly disordered so that it is effectively a spherical anion of radius 1.53 Å (between and in size). At room temperature, the groups are ordered and the environment about the centers is distorted, with distances ranging from 2.69 to 3.15 Å, depending on the orientation of the OH group. KOH forms a series of crystalline hydrates, namely the monohydrate , the dihydrate and the tetrahydrate . About 121 g of KOH dissolve in 100 mL water at room temperature, which contrasts with 100 g/100 mL for NaOH. Thus on a molar basis, NaOH is slightly more soluble than KOH. Lower molecular-weight alcohols such as methanol, ethanol, and propanols are also excellent solvents. They participate in an acid-base equilibrium. In the case of methanol the potassium methoxide (methylate) forms: Because of its high affinity for water, KOH serves as a desiccant in the laboratory.

About this result
This page is automatically generated and may contain information that is not correct, complete, up-to-date, or relevant to your search query. The same applies to every other page on this website. Please make sure to verify the information with EPFL's official sources.
Related courses (8)
ENV-200: Environmental chemistry
This course provides students with an overview over the basics of environmental chemistry. This includes the chemistry of natural systems, as well as the fate of anthropogenic chemicals in natural sys
ChE-340: The engineering of chemical reactions
Ce cours applique les concepts de la cinétique chimique et des bilans de masse et d'énergie pour résoudre les problèmes de génie des réactions chimiques, en mettant l'accent sur les applications indus
CH-222: Coordination chemistry
Fundamental knowledge of coordination compounds.
Show more
Related publications (78)
Related concepts (25)
Lye
A lye is an alkali metal hydroxide traditionally obtained by leaching wood ashes (potassium), or a strong alkali which is highly soluble in water producing caustic basic solutions. "Lye" most commonly refers to sodium hydroxide (NaOH), but historically has been used for potassium hydroxide (KOH). Today, lye is commercially manufactured using a membrane cell chloralkali process. It is supplied in various forms such as flakes, pellets, microbeads, coarse powder or a solution.
Potassium carbonate
Potassium carbonate is the inorganic compound with the formula K2CO3. It is a white salt, which is soluble in water and forms a strongly alkaline solution. It is deliquescent, often appearing as a damp or wet solid. Potassium carbonate is mainly used in the production of soap and glass. Potassium carbonate is the primary component of potash and the more refined pearl ash or salts of tartar. The very ever first patent issued by the US Patent Office was awarded to Samuel Hopkins in 1790 for an improved method of making potash and pearl ash.
Potassium chloride
Potassium chloride (KCl, or potassium salt) is a metal halide salt composed of potassium and chlorine. It is odorless and has a white or colorless vitreous crystal appearance. The solid dissolves readily in water, and its solutions have a salt-like taste. Potassium chloride can be obtained from ancient dried lake deposits. KCl is used as a fertilizer, in medicine, in scientific applications, domestic water softeners (as a substitute for sodium chloride salt), and in food processing, where it may be known as E number additive E508.
Show more
Related MOOCs (2)
Sorption and transport in cementitious materials
Learn how to study and improve the durability of cementitious materials.
Cement Chemistry and Sustainable Cementitious Materials
Learn the basics of cement chemistry and laboratory best practices for assessment of its key properties.

Graph Chatbot

Chat with Graph Search

Ask any question about EPFL courses, lectures, exercises, research, news, etc. or try the example questions below.

DISCLAIMER: The Graph Chatbot is not programmed to provide explicit or categorical answers to your questions. Rather, it transforms your questions into API requests that are distributed across the various IT services officially administered by EPFL. Its purpose is solely to collect and recommend relevant references to content that you can explore to help you answer your questions.