From Wikipedia, the không tính phí encyclopedia

Bạn đang xem: zn(oh)2

Zinc hydroxide
Zinc hydroxide
IUPAC name

Zinc hydroxide


CAS Number

  • 20427-58-1 check

3D model (JSmol)

  • Interactive image
  • 7988510 check
ECHA InfoCard 100.039.816 Edit this at Wikidata

PubChem CID

  • 9812759
  • OXK3V8KJ7L check

CompTox Dashboard (EPA)

  • DTXSID7042516 Edit this at Wikidata


  • InChI=1S/2H2O.Zn/h2*1H2;/q;;+2/p-2 check


  • InChI=1/2H2O.Zn/h2*1H2;/q;;+2/p-2



  • [Zn+2].[OH-].[OH-]


Chemical formula

Molar mass 99.424 g/mol
Appearance white powder
Density 3.053 g/cm3, solid
Melting point 125 °C (257 °F; 398 K) (decomposition)

Solubility in water

slightly soluble

Solubility product (Ksp)

Solubility in alcohol insoluble

Xem thêm: vẽ sơ đồ online

Magnetic susceptibility (χ)

−67.0·10−6 cm3/mol

Std enthalpy of
formation fH298)

−642 kJ·mol−1[1]
Flash point Non-flammable
Related compounds

Other anions

Zinc oxide

Other cations

Cadmium hydroxide

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

check verify (what is check☒ ?)

Infobox references

Zinc hydroxide Zn(OH)2 is an inorganic chemical compound. It also occurs naturally as 3 rare minerals: wülfingite (orthorhombic), ashoverite and sweetite (both tetragonal).

Like the hydroxides of other metals, such as lead, aluminium, beryllium, tin cậy and chromium, Zinc hydroxide (and Zinc oxide), is amphoteric. Thus it will dissolve readily in a dilute solution of a strong acid, such as HCl, and also in a solution of an alkali such as sodium hydroxide.


It can be prepared by adding sodium hydroxide solution, but not in excess, đồ sộ a solution of any zinc salt. A white precipitate will be seen:

Zn2+ + 2 OH → Zn(OH)2.

Zn2+ is known đồ sộ khuông hexa-aqua ions at high water concentrations and tetra-aqua ions at low concentrations of water [2] and, thus, this reaction may be better written as the reaction of the aquated ion with hydroxide through donation of a proton, as follows.

Zn2+(OH2)4(aq) + OH(aq) → Zn2+(OH2)3OH(aq) + H2O(l)

Subsequent reactions discussed below can also, therefore, be considered as reactions with the aquated zinc ion and one can adjust them accordingly. However, for simplicity, the water molecules are omitted from here-on.

If excess sodium hydroxide is added, the precipitate of zinc hydroxide will dissolve, forming a colorless solution of zincate ion:

Zn(OH)2 + 2 OH → Zn(OH)42−.

This property can be used as a test for zinc ions in solution, but it is not exclusive, since aluminium and lead compounds behave in a very similar manner. Unlike the hydroxides of aluminium and lead, zinc hydroxide also dissolves in excess aqueous ammonia đồ sộ khuông a colorless, water-soluble ammine complex.

Zinc hydroxide will dissolve because the ion is normally surrounded by water ligands; when excess sodium hydroxide is added đồ sộ the solution the hydroxide ions will reduce the complex đồ sộ 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 sánh that it dissolves.


One major use is as an absorbent in surgical dressings. It is also used đồ sộ find zinc salts by mixing sodium hydroxide with the suspect salt.

Xem thêm: cách cân bằng phương trình


  1. ^ Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. p. A23. ISBN 0-618-94690-X.
  2. ^ Sze, Yu-Keung, and Donald E. Irish. "Vibrational spectral studies of ion-ion and ion-solvent interactions. I. Zinc nitrate in water." Journal of Solution Chemistry 7.6 (1978): 395-415.
  • Chemistry in Context - By Graham Hill, John Holman (pp. 283,284)