Zinc hydroxide

Crystal structure
__ Zn 2+      __ O -      __ H +
General
Surname	Zinc hydroxide
other names	Zinc (II) hydroxide
Ratio formula	Zn (OH) 2
Brief description	colorless, odorless powder
External identifiers / databases
CAS number 20427-58-1 EC number 243-814-3 ECHA InfoCard 100,039,816 PubChem 9812759 ChemSpider 7988510 Wikidata Q204820
properties
Molar mass	99.41 g mol −1
Physical state	firmly
density	3.11 g cm −3
Melting point	134 ° C
solubility	sparingly soluble in water (648 mg l −1 at 20 ° C)
safety instructions
GHS labeling of hazardous substances Caution H and P phrases H: 410 P: 273-391-501
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Zinc hydroxide is a chemical compound from the group of hydroxides with the formula Zn (OH) ₂ . It is a non-flammable, colorless and odorless powder that is sparingly soluble in water.

Occurrence

Zinc hydroxide occurs naturally in three rare minerals . Wülfingite (orthorhombic), Ashoverite and Sweetite (both tetragonal). It is also formed when alkaline-manganese batteries are discharged and is one of the main components of white rust .

Extraction and presentation

Zinc hydroxide can be obtained by reacting zinc (II) chloride with sodium hydroxide .

${\displaystyle \mathrm {ZnCl_{2}+2\ NaOH\longrightarrow Zn(OH)_{2}+2\ NaCl} }$

In general, zinc hydroxide precipitates out as a gelatinous mass from solutions which contain both Zn ²⁺ and (OH) ^- ions. This is used to detect zinc cations .

properties

Zinc hydroxide (like many metal hydroxides) is sparingly soluble in water. It is an amphoteric hydroxide, so it is soluble in both acidic and alkaline media. In acids it dissolves with the formation of [Zn (H ₂ O) ₆ ] ²⁺ ions, in concentrated bases with the formation of hydroxozincate ions [Zn (OH) ₄ ] ²⁻ . It has an orthorhombic crystal structure with the space group P 2 ₁ 2 ₁ 2 ₁ (space group no. 19) , a = 5.17  Å , b = 8.55 Å, c = 4.93 Å, although there are five other crystalline ones There are forms that are, however, unstable and, under normal conditions, change into zinc hydroxide (more precisely ε-zinc hydroxide). The oxo and hydroxo acids of zinc theoretically formed when zinc hydroxide is dissolved are known as zincates .

use

Zinc hydroxide can be used to make zinc oxide .

Related links

• Zinc hydroxide chloride Zn (OH) Cl
• Zinc hydroxide phosphate Zn ₂ (OH) PO ₄

Individual evidence

1. ↑ ^{a b c d e f} Entry on zinc hydroxide in the GESTIS substance database of the IFA , accessed on February 1, 2016(JavaScript required) .
2. ↑ ^{a b} Georg Brauer (Ed.), With the collaboration of Marianne Baudler u a .: Handbook of Preparative Inorganic Chemistry. 3rd, revised edition. Volume II, Ferdinand Enke, Stuttgart 1978, ISBN 3-432-87813-3 , p. 1026.
3. ↑ Erwin Riedel: Inorganic Chemistry . 6th edition, ISBN 978-3-11-018168-5 .
4. ↑ Georg Brauer (Ed.), With the collaboration of Marianne Baudler a. a .: Handbook of Preparative Inorganic Chemistry. 3rd, revised edition. Volume II, Ferdinand Enke, Stuttgart 1978, ISBN 3-432-87813-3 .