Sodium hydroxide in the context of Ionic salt

In chemistry, a salt or ionic compound is a chemical compound consisting of an assembly of positively charged ions (cations) and negatively charged ions (anions), which results in a compound with no net electric charge. The constituent ions are held together by electrostatic forces termed ionic bonds.

The component ions in a salt can be either inorganic, such as chloride (Cl), or organic, such as acetate (CH
₃COO
). Each ion can be either monatomic, such as sodium (Na) and chloride (Cl) in sodium chloride, or polyatomic, such as ammonium (NH
₄) and carbonate (CO
₃) ions in ammonium carbonate. Salts containing basic ions hydroxide (OH) or oxide (O) are classified as bases, such as sodium hydroxide and potassium oxide.

Hydroxide is a diatomic anion with chemical formula OH. It consists of an oxygen and hydrogen atom held together by a single covalent bond, and carries a negative electric charge. It is an important but usually minor constituent of water. It functions as a base, a ligand, a nucleophile, and a catalyst. The hydroxide ion forms salts, some of which dissociate in aqueous solution, liberating solvated hydroxide ions. Sodium hydroxide is a multi-million-ton per annum commodity chemical.The corresponding electrically neutral compound HO is the hydroxyl radical. The corresponding covalently bound group −OH of atoms is the hydroxy group.Both the hydroxide ion and hydroxy group are nucleophiles and can act as catalysts in organic chemistry.

Many inorganic substances which bear the word hydroxide in their names are not ionic compounds of the hydroxide ion, but covalent compounds which contain hydroxy groups.

Sodium is a chemical element; it has symbol Na (from Neo-Latin natrium) and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable isotope is Na. The free metal does not occur in nature and must be prepared from compounds. Sodium is the sixth most abundant element in the Earth's crust and exists in numerous minerals such as feldspars, sodalite, and halite (NaCl). Many salts of sodium are highly water-soluble: sodium ions have been leached by the action of water from the Earth's minerals over eons, and thus sodium and chlorine are the most common dissolved elements by weight in the oceans.

Sodium was first isolated by Humphry Davy in 1807 by the electrolysis of sodium hydroxide. Among many other useful sodium compounds, sodium hydroxide (lye) is used in soap manufacture, and sodium chloride (edible salt) is a de-icing agent and a nutrient for animals including humans.

In chemistry, there are three definitions in common use of the word "base": Arrhenius bases, Brønsted bases, and Lewis bases. All definitions agree that bases are substances that react with acids, as originally proposed by G.-F. Rouelle in the mid-18th century.

In 1884, Svante Arrhenius proposed that a base is a substance which dissociates in aqueous solution to form hydroxide ions OH. These ions can react with hydrogen ions (H according to Arrhenius) from the dissociation of acids to form water in an acid–base reaction. A base was therefore a metal hydroxide such as NaOH or Ca(OH)₂. Such aqueous hydroxide solutions were also described by certain characteristic properties. They are slippery to the touch, can taste bitter and change the color of pH indicators (e.g., turn red litmus paper blue).

Dross is a mass of solid impurities floating on a molten metal or dispersed in the metal, such as in wrought iron. It forms on the surface of low-melting-point metals such as tin, lead, zinc or aluminium or alloys by oxidation of the metal. For higher melting point metals and alloys such as steel and silver, oxidized impurities melt and float making them easy to pour off.

With wrought iron, hammering and later rolling remove some dross.With tin and lead the dross can be removed by adding sodium hydroxide pellets, which dissolve the oxides and form a slag. If floating, dross can also be skimmed off.

Sodium salts are salts composed of a sodium cation and any anion. The anion may be the conjugate base of some inorganic or organic acids, or any monatomic or polyatomic anion. They can be formed by the neutralization of acids with sodium hydroxide.

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 utilize its caustic nature and its reactivity toward acids. About 2.5 million tonnes were produced in 2023. 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.

Saponification is a process of cleaving esters into carboxylate salts and alcohols by the action of aqueous alkali. Typically aqueous sodium hydroxide solutions are used. It is an important type of alkaline hydrolysis. When the carboxylate is a long chain, its salt is called a soap. The saponification of ethyl acetate gives sodium acetate and ethanol:

An acid attack, also called acid throwing, vitriol attack, or vitriolage, is a form of violent assault involving the act of throwing acid or a similarly corrosive substance onto the body of another "with the intention to disfigure, maim, torture, or kill". Perpetrators of these attacks throw corrosive liquids at their victims, usually at their faces, burning them, and damaging skin tissue, often exposing and sometimes dissolving the bones. Acid attacks can lead to partial or complete blindness.

The most common types of acid used in these attacks are sulfuric and nitric acid. Hydrochloric acid is sometimes used but is much less damaging. Aqueous solutions of strongly alkaline materials, such as caustic soda (sodium hydroxide) or ammonia, are used as well, particularly in areas where strong acids are controlled substances.

Lye is the common name of various alkaline solutions, including soda lye (a solution of sodium hydroxide) and potash lye (a solution of potassium hydroxide). Lyes are used as cleaning products, as ingredients in soapmaking, and in various other contexts.

A pretzel (/ˈprɛtsəl/ PRET-səl; from German: Breze or Brezel, pronounced [ˈbʁeːtsl̩] or [ˈbʁɛtsl̩]; Bavarian: Brezn) is a type of baked pastry made from dough that is commonly shaped into a knot. The traditional pretzel shape is a distinctive symmetrical form, with the ends of a long strip of dough intertwined and then twisted back onto itself in a particular way (a pretzel loop or pretzel bow). Today, pretzels come in various shapes, textures, and colors, but the original soft pretzel remains one of the most common pretzel types.

Salt is the most common seasoning, or topping, for pretzels, complementing the washing soda or lye treatment that gives pretzels their traditional skin and flavor acquired through the Maillard reaction. Other toppings are mustard, cheeses, sugar, chocolate, cinnamon, sweet glazing, seeds, and nuts. Regional specialties like Spundekäs have been designed to go along with pretzels. Varieties of pretzels include soft pretzels, which should be eaten shortly after preparation, and hard-baked pretzels, which have a long shelf life.

The kraft process (also known as kraft pulping or sulfate process) is a process for conversion of wood into wood pulp, which consists of almost pure cellulose fibres, the main component of paper. The kraft process involves treatment of wood chips with a hot mixture of water, sodium hydroxide (NaOH), and sodium sulfide (Na₂S), known as white liquor, that breaks the bonds that link lignin, hemicellulose, and cellulose. The technology entails several steps, both mechanical and chemical. It is the dominant method for producing paper. In some situations, the process has been controversial because kraft plants can release odorous products and in some situations produce substantial liquid wastes.

The process name is derived from the German word Kraft, meaning 'strength' in this context, due to the strength of the kraft paper produced using this process.

Dutch processed cocoa, Dutched cocoa, or alkalized cocoa, is made from cocoa solids that have been treated with an alkalizing agent to reduce the natural acidity of cocoa, giving it a less bitter taste and darker colour compared to "natural cocoa" extracted with the Broma process. Alkalizing agents employed vary, but include potassium carbonate (E501), sodium carbonate (E500), and sodium hydroxide (E525).

Dutching greatly reduces the levels of certain phytochemicals in cocoa. It forms the basis for much of modern chocolate, and is used in ice cream, hot chocolate, and baking.