Lead(II) hydroxide
Encyclopedia
Lead hydroxide, Pb(OH)2, is a hydroxide
of lead
, with lead in oxidation state
+2. Although it appears a fundamentally simple compound, it is doubtful if lead hydroxide is stable as a solid phase. Lead basic carbonate
(PbCO3·2Pb(OH)2) or lead(II) oxide
(PbO) is encountered in practice where lead hydroxide is expected. This has been a subject of considerable confusion in the past.
When an alkali hydroxide is added to a solution of a lead(II) salt, then a hydrated lead oxide PbO·xH2O (with x < 1) is obtained. Careful hydrolysis
of lead(II) acetate
solution yields a crystalline product with a formula 6PbO·2H2O = Pb6O4(OH)4.
In solution, lead(II) hydroxide is a somewhat weak base, forming lead(II) ion
, Pb2+, under weakly acidic conditions. This cation hydrolyzes and, under progressively increasing alkaline conditions, forms Pb(OH)+, Pb(OH)2(aqueous), Pb(OH)3−, and other species, including several polynuclear species, e.g., Pb4(OH)44+, Pb3(OH)42+, Pb6O(OH)64+.
Hydroxide
Hydroxide is a diatomic anion with chemical formula OH−. It consists of an oxygen and a hydrogen atom held together by a covalent bond, and carrying a negative electric charge. It is an important but usually minor constituent of water. It functions as a base, as a ligand, a nucleophile, and a...
of lead
Lead
Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
, with lead in oxidation state
Oxidation state
In chemistry, the oxidation state is an indicator of the degree of oxidation of an atom in a chemical compound. The formal oxidation state is the hypothetical charge that an atom would have if all bonds to atoms of different elements were 100% ionic. Oxidation states are typically represented by...
+2. Although it appears a fundamentally simple compound, it is doubtful if lead hydroxide is stable as a solid phase. Lead basic carbonate
White lead
White lead is the chemical compound 2·Pb2. It was formerly used as an ingredient for lead paint and a cosmetic called Venetian Ceruse, because its opaque quality made it a good pigment. However, it tended to cause lead poisoning, and its use has been banned in most countries.White lead has been...
(PbCO3·2Pb(OH)2) or lead(II) oxide
Lead(II) oxide
Lead oxide is the inorganic compound with the formula PbO. Lead oxide occurs in two polymorphs, red, having a tetragonal crystal structure and yellow, having an orthorhombic crystal structure...
(PbO) is encountered in practice where lead hydroxide is expected. This has been a subject of considerable confusion in the past.
When an alkali hydroxide is added to a solution of a lead(II) salt, then a hydrated lead oxide PbO·xH2O (with x < 1) is obtained. Careful hydrolysis
Hydrolysis
Hydrolysis is a chemical reaction during which molecules of water are split into hydrogen cations and hydroxide anions in the process of a chemical mechanism. It is the type of reaction that is used to break down certain polymers, especially those made by condensation polymerization...
of lead(II) acetate
Lead(II) acetate
Lead acetate , also known as lead acetate, lead diacetate, plumbous acetate, sugar of lead, lead sugar, salt of Saturn, and Goulard's powder, is a white crystalline chemical compound with a sweetish taste. It is made by treating lead oxide with acetic acid. Like other lead compounds, it is toxic...
solution yields a crystalline product with a formula 6PbO·2H2O = Pb6O4(OH)4.
In solution, lead(II) hydroxide is a somewhat weak base, forming lead(II) ion
Ion
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...
, Pb2+, under weakly acidic conditions. This cation hydrolyzes and, under progressively increasing alkaline conditions, forms Pb(OH)+, Pb(OH)2(aqueous), Pb(OH)3−, and other species, including several polynuclear species, e.g., Pb4(OH)44+, Pb3(OH)42+, Pb6O(OH)64+.