Aluminium hydroxide
General
Systematic name	Aluminium(III) hydroxide
Other names	Aluminium hydroxide, Hydrated alumina
Molecular formula	Al(OH)3
Molar mass	78.00344 g/mol
Appearance	White amorphous powder.
CAS number	[[21645-51-2]]
Properties
Density and phase	2.4 g/cm³, solid.
Solubility in water	Insoluble.
Melting point	300°C
Boiling point	?°C
Acidity (pKa)	N/A
Hazards
MSDS	External MSDS
EU classification	Irritant (I)
NFPA 704	N/A
R-phrases	R36, R37, R38
S-phrases	S26, S36
Flash point	Non-flammable.
RTECS number	N/A
Supplementary data page
Structure & properties	n, εr, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Related compounds
Other anions	None.
Related compounds	Sodium oxide, aluminium oxide hydroxide.
Except where noted otherwise, data are given for materials in their standard state (at 25°C, 100 kPa) Infobox disclaimer and references

Aluminium hydroxide, Al(OH)₃, is the most stable form of aluminium in normal conditions. As found in nature it is known as the mineral gibbsite. Closely related are aluminium oxide hydroxide, AlO(OH), and aluminium oxide, Al₂O₃, differing only by loss of water. These compounds together are the major components of the aluminium ore, bauxite. Image File history File links No higher resolution available. ... IUPAC nomenclature is a system of naming chemical compounds and of describing the science of chemistry in general. ... A chemical formula (also called molecular formula) is a concise way of expressing information about the atoms that constitute a particular chemical compound. ... Molar mass is the mass of one mole of a chemical element or chemical compound. ... An amorphous solid is a solid in which there is no long-range order of the positions of the atoms. ... CAS registry numbers are unique numerical identifiers for chemical compounds, polymers, biological sequences, mixtures and alloys. ... In physics, density is defined as mass m per unit volume V. Mathematically, it is expressed as where, in SI units: ρ (rho) is the density of the substance, measured in kg·m-3 m is the mass of the substance, measured in kg V is the volume of the substance... In the physical sciences, a phase is a set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties (i. ... It has been suggested that this article or section be merged with Solution. ... This article describes water from a scientific and technical perspective. ... The melting point of a crystalline solid is the temperature at which it changes state from solid to liquid. ... The boiling point of a substance is the temperature at which it can change its state from a liquid to a gas throughout the bulk of the liquid at a given pressure. ... In chemistry and biochemistry, the acid dissociation constant, the acidity constant, or the acid-ionization constant (Ka) is a specific type of equilibrium constant that indicates the extent of dissociation of hydronium ions from an acid. ... An example MSDS in a US format provides guidance for handling a hazardous substance and information on its composition and properties. ... Council Directive 67/548/EEC of 27 June 1967 on the approximation of laws, regulations and administrative provisions relating to the classification, packaging and labelling of dangerous substances (as amended) is the main source of European Union law concerning chemical safety. ... NFPA 704 is a standard maintained by the U.S. National Fire Protection Association. ... R-phrases are defined in Annex III of European Union Directive 67/548/EEC: Nature of special risks attributed to dangerous substances and preparations. ... S-phrases are defined in Annex IV of European Union Directive 67/548/EEC: Safety advice concerning dangerous substances and preparations. ... The flash point of a flammable liquid is the lowest temperature at which it can form an ignitable mixture with air. ... RTECS, also known as Registry of Toxic Effects of Chemical Substances, is a database of toxicity information compiled from the open scientific literature that is available for charge. ... The refractive index (or index of refraction) of a material is the factor by which the phase velocity of electromagnetic radiation is slowed in that material, relative to its velocity in a vacuum. ... The dielectric constant εr (represented as or K in some cases) is defined as the ratio: where εs is the static permittivity of the material in question, and ε0 is the vacuum permittivity. ... Ultraviolet-Visible Spectroscopy or Ultraviolet-Visible Spectrophotometry (UV/ VIS) involves the spectroscopy of photons (spectrophotometry). ... Infrared spectroscopy (IR Spectroscopy) is the subset of spectroscopy that deals with the infrared region of the electromagnetic spectrum. ... It has been suggested that NMR Data Processing be merged into this article or section. ... Mass spectrometry (also known as mass spectroscopy (deprecated)[1] or in common speech mass-spec) is an analytical technique used to measure the mass-to-charge ratio of ions. ... “Multivalent” redirects here. ... Sodium oxide has formula Na2O. It is also called sodium(I) oxide, disodium oxide, sodium monoxide, and soda. ... Aluminium oxide hydroxide is found as one of two well defined crystalline phases, which are also known as the minerals boehmite and diaspore. ... In chemistry, the standard state of a material is its state at 1 bar (100 kilopascals) and 25 degrees Celsius (298. ... General Name, Symbol, Number aluminium, Al, 13 Chemical series poor metals Group, Period, Block 13, 3, p Appearance silvery Atomic mass 26. ... Gibbsite, Al(OH)3, is an important ore of aluminium and is one of three minerals that make up the rock bauxite. ... Aluminium oxide hydroxide is found as one of two well defined crystalline phases, which are also known as the minerals boehmite and diaspore. ... Alumina redirects here. ... Iron ore (Banded iron formation) Manganese ore Lead ore Gold ore An ore is a volume of rock containing components or minerals in a mode of occurrence which renders it valuable for mining. ... Bauxite with penny Bauxite with core of unweathered rock Bauxite is an aluminium ore which consists largely of the Al minerals gibbsite Al(OH)3, boehmite and diaspore AlOOH, together with the iron oxides goethite and hematite, the clay mineral kaolinite and small amounts of anatase TiO2. ...

The character of 'aluminium hydroxide' has been controversial. It is safe to say that a simple scheme of Al³⁺ ions and OH^- ions is oversimplified. More and less hydrated forms are very common. Some people write Al₂O₃.xH₂O instead.

Reactions

Aluminium hydroxide is amphoteric. In strongly acid conditions, Al(OH)₂⁺ is formed; in strongly basic conditions, Al(OH)₄^- is formed. These are the main ions in dilute solutions; in concentrated solutions, polymeric ions are formed which can be quite complex. In chemistry, an amphoteric substance is one that can react with either an acid or base (more generally, the word describes something made of, or acting like, two components). ...

Salts of the anion Al(OH)₄^- (or similar, such as AlO₂^-) are sometimes called aluminates. An aluminate is a compound containing aluminium and oxygen with more electropositive elements. ...

Al(OH)₃ has a molar mass of 78.01.

When used, aluminum hydroxide neutralizes the excess acid. For example, Al(OH)₃ + 3HCl yields AlCl₃ + 3H₂O.

Pharmacology

Pharmacologically this compound, also known as Alu-Cap or Aludrox, is used as an antacid. It binds with the excess acid in the stomach, thus reducing its acidity. This decrease of acidity of the contents of the stomach may in turn help to relieve the symptoms of ulcers, heartburn or dyspepsia. It can also cause constipation and is therefore often used with magnesium carbonate. This compound is also used to control phosphate levels in the blood for people suffering from kidney failure. However, there are unverified claims that excessive consumption of aluminium is a cause of Alzheimer's disease. A Bottle of Antacid tablets An antacid is any substance, generally a base, which counteracts stomach acidity. ... An ulcer (from Latin ulcus) is an open sore of the skin, eyes or mucous membrane, often caused by an initial abrasion and generally maintained by an inflammation and/or an infection. ... Magnesium carbonate, MgCO3, is a white solid that occurs in nature as a mineral. ...

References

Galbraith, A; Bullock, S; Manias, E. Hunt, B. & Richards, A. (1999). Fundamentals of pharmacology: a text for nurses and health professionals. Harlow: Pearson Education Ltd. p482.

External links

• International Chemical Safety Card 0373
• External MSDS Sheet.

• Links to external chemical sources