Instruct: Given a question, retrieve passages that can help answer the question.
Query: What is the symbol for hydroxide?
Hydroxide is a diatomic anion with chemical formula OH−. It consists of an oxygen and hydrogen atom held together by a 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. A hydroxide attached to a strongly electropositive center may itself ionize, liberating a hydrogen cation (H+), making the parent compound an acid.
Thallium(I) hydroxide, also called thallous hydroxide, TlOH, is a hydroxide of thallium, with thallium in oxidation state +1. Thallous hydroxide is a strong base; it is changed to thallous ion, Tl, except in strongly basic conditions. Tl resembles an alkali metal ion, A, such as Li or K.
Zinc hydroxide will dissolve because the ion is normally surrounded by water ligands; when excess sodium hydroxide is added to the solution the hydroxide ions will reduce the complex to a −2 charge and make it soluble. When excess ammonia is added, it sets up an equilibrium which provides hydroxide ions; the formation of hydroxide ions causes a similar reaction as sodium hydroxide and creates a +2 charged complex with a co-ordination number of 4 with the ammonia ligands - this makes the complex soluble so that it dissolves. 
Natural magnesium hydroxide (brucite) is used commercially as a fire retardant. Most industrially used magnesium hydroxide is produced synthetically. Like aluminium hydroxide, solid magnesium hydroxide has smoke suppressing and flame retardant properties. This property is attributable to the endothermic decomposition it undergoes at 332 °C (630 °F):
Rubidium hydroxide is rarely used in industrial processes because potassium hydroxide and sodium hydroxide can perform nearly all the industrial functions of rubidium hydroxide in a less violent and hence safer way.
A typical school demonstration demonstrates what happens when a piece of an alkali metal is introduced to a bowl of water. A vigorous reaction occurs, producing hydrogen gas and the specific alkali hydroxide. For example, if sodium is the alkali metal:
Copper(II) hydroxide is the hydroxide of copper with the chemical formula of Cu(OH). It is a pale greenish blue or bluish green solid. Some forms of copper(II) hydroxide are sold as "stabilized" copper hydroxide, although they likely consist of a mixture of copper(II) carbonate and hydroxide. Copper hydroxide is a weak base.
Thallium(III) hydroxide, Tl(OH), also known as thallic hydroxide, is a hydroxide of thallium. It is a white solid.
Historically, KOH was made by adding potassium carbonate to a strong solution of calcium hydroxide (slaked lime) The salt metathesis reaction results in precipitation of solid calcium carbonate, leaving potassium hydroxide in solution:
Filtering off the precipitated calcium carbonate and boiling down the solution gives potassium hydroxide ("calcinated or caustic potash"). This method of producing potassium hydroxide remained dominnt until the late 19th century, when it was largely replaced by the current method of electrolysis of potassium chloride solutions. The method is analogous to the manufacture of sodium hydroxide (see chloralkali process):
Unlike sodium hydroxide, the hydroxides of most transition metals are insoluble, and therefore sodium hydroxide can be used to precipitate transition metal hydroxides. The following colours are observed: blue-copper, green-iron(II), yellow/brown-iron(III). Zinc and lead salts dissolve in excess sodium hydroxide to give a clear solution of NaZnO or NaPbO.
Aqueous potassium hydroxide is employed as the electrolyte in alkaline batteries based on nickel-cadmium, nickel-hydrogen, and manganese dioxide-zinc. Potassium hydroxide is preferred over sodium hydroxide because its solutions are more conductive. The nickel–metal hydride batteries in the Toyota Prius use a mixture of potassium hydroxide and sodium hydroxide. Nickel–iron batteries also use potassium hydroxide electrolyte.
Caesium hydroxide or cesium hydroxide (CsOH) is a chemical compound consisting of caesium ions and hydroxide ions. It is a strong base (pK=-1.76), much like the other alkali metal hydroxides such as sodium hydroxide and potassium hydroxide. In fact, caesium hydroxide is corrosive enough to quickly corrode through glass.
Some organic bases, such as tetramethylammonium hydroxide, tetrabutylammonium hydroxide, or choline hydroxide are hydroxide donors rather than proton acceptors like the above compounds. However, they are not always stable. Choline hydroxide, for example, is metastable and slowly breaks down to release trimethylamine.
The most common alkali hydroxide is sodium hydroxide, which is readily available in most hardware stores in products such as a drain cleaner. Another common alkali hydroxide is potassium hydroxide. This is available as a solution used for cleaning terraces and other areas made out of wood.
The solubility in water of the other hydroxides in this group increases with increasing atomic number.[18] Magnesium hydroxide Mg(OH)2 is a strong base (up to the limit of its solubility, which is very low in pure water), as are the hydroxides of the heavier alkaline earths: calcium hydroxide, strontium hydroxide, and barium hydroxide. A solution or suspension of calcium hydroxide is known as limewater and can be used to test for the weak acid carbon dioxide. The reaction Ca(OH)2 + CO2 ⇌ Ca2+ + HCO− 3 + OH− illustrates the basicity of calcium hydroxide. Soda lime, which is a mixture of the strong bases NaOH and KOH with Ca(OH)2, is used as a CO2 absorbent.
Radium oxide (RaO) has not been characterized well past its existence, despite oxides being common compounds for the other alkaline earth metals. Radium hydroxide (Ra(OH)) is the most readily soluble among the alkaline earth hydroxides and is a stronger base than its barium congener, barium hydroxide. It is also more soluble than actinium hydroxide and thorium hydroxide: these three adjacent hydroxides may be separated by precipitating them with ammonia.
Sodium hydroxide, potassium hydroxide, silver hydroxide, ammonium hydroxide, etc
Barium hydroxide, magnesium hydroxide, calcium hydroxide, zinc hydroxide, iron(II) hydroxide, tin(II) hydroxide, lead(II) hydroxide, copper(II) hydroxide, etc.
The alkali metal hydroxides are the strongest of all bases.The order of basicity increases down the group, i.e., LiOH is the least basic and CsOH, the most basic hydroxide. It is due to the property of bases to donate ion and due to small size and high lattice enthalpy of Li, it donates less and large size and low lattice enthalpy of Cs, Cesium hydroxide donates more ions than any other hydroxide. All the alkali metal hydroxides are white crystalline solids and dissolve freely in water with evolution of much heat.
The net effect is that the concentration of sodium chloride in the outside cells decreases and the concentration of sodium hydroxide in the center cell increases. As the process continues some sodium hydroxide solution is withdrawn from center cell as output product and is replaced with water. Sodium chloride is added to the outside cells to replace what has been electrolyzed.
A common use of sodium hydroxide is in the production of parts washer detergents. Parts washer detergents based on sodium hydroxide are some of the most aggressive parts washer cleaning chemicals. The sodium hydroxide-based detergents include surfactants, rust inhibitors and defoamers. A parts washer heats water and the detergent in a closed cabinet and then sprays the heated sodium hydroxide and hot water at pressure against dirty parts for degreasing applications. Sodium hydroxide used in this manner replaced many solvent-based systems in the early 1990s when trichloroethane was outlawed by the Montreal Protocol. Water and sodium hydroxide detergent-based parts washers are considered to be an environmental improvement over the solvent-based cleaning methods.
The alkali hydroxides are a class of chemical compounds which are composed of an alkali metal cation and the hydroxide anion (OH). The alkali hydroxides are:
Virtually all the aluminium hydroxide used commercially is manufactured by the Bayer process which involves dissolving bauxite in sodium hydroxide at temperatures up to . The waste solid, bauxite tailings, is removed and aluminium hydroxide is precipitated from the remaining solution of sodium aluminate. This aluminium hydroxide can be converted to aluminium oxide or alumina by calcination.
If, however, the electronegativity of X is low, then the compound is dissociated to ions according to the latter chemical equation, and XOH is an alkaline hydroxide. Examples of such compounds are sodium hydroxide NaOH and calcium hydroxide Ca(OH). Owing to the high electronegativity of oxygen, however, most of the common oxobases, such as sodium hydroxide, while strongly basic in water, are only moderately basic in comparison to other bases. For example, the pKa of the conjugate acid of sodium hydroxide, water, is 15.7, while that of sodium amide, ammonia, is closer to 40, making sodium hydroxide a much weaker base than sodium amide.
Ammonia solution, also known as ammonia water, ammonium hydroxide, ammoniacal liquor, ammonia liquor, aqua ammonia, aqueous ammonia, or (inaccurately) ammonia, is a solution of ammonia in water. It can be denoted by the symbols NH(aq). Although the name ammonium hydroxide suggests an alkali with composition [NH][OH], it is actually impossible to isolate samples of NHOH. The ions NH and OH do not account for a significant fraction of the total amount of ammonia except in extremely dilute solutions.