Copper (II) hydroxide
Crystal structure | ||||||||||||||||
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__ Cu 2+ __ O 2− __ H + | ||||||||||||||||
General | ||||||||||||||||
Surname | Copper (II) hydroxide | |||||||||||||||
other names |
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Ratio formula | Cu (OH) 2 | |||||||||||||||
Brief description |
odorless light blue powder |
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properties | ||||||||||||||||
Molar mass | 97.56 g mol −1 | |||||||||||||||
Physical state |
firmly |
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density |
3.37 g cm −3 |
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Melting point |
229 ° C (decomposition) |
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solubility |
almost insoluble in water (2.9 mg l −1 ) |
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safety instructions | ||||||||||||||||
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MAK |
0.1 mg m −3 |
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Toxicological data | ||||||||||||||||
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . |
Copper (II) hydroxide is a hydroxide - salt of copper . It is a blue solid that, alone or in combination, forms the color pigment Bremer Blau (also called lime blue ).
Occurrence
Of course, copper (II) hydroxide occurs as part of the green patina of copper, which consists of basic copper carbonate . A rare pure copper (II) hydroxide mineral is spertiniite .
Extraction and presentation
Copper hydroxide can be produced by reacting copper salts with alkaline solutions . Typically, copper sulfate pentahydrate is dissolved in water and converted to copper hydroxide and sodium sulfate by adding sodium hydroxide while cooling .
Alternatively, copper hydroxide can also be produced by the electrochemical conversion of copper into water.
properties
Copper (II) hydroxide is insoluble in cold water. The compound is soluble in concentrated alkaline solutions. Hydroxo complexes such as the deep blue [Cu (OH) 4 ] 2− are formed . Freshly precipitated copper (II) hydroxide is also soluble in ammonia solution with the formation of the complex compound tetraammine copper (II) hydroxide. The reaction with mineral acids leads to the corresponding copper (II) salts.
When heated, (freshly precipitated) copper (II) hydroxide breaks down into copper (II) oxide and water .
With careful drying (100 ° C.), almost anhydrous copper (II) hydroxide is obtained in crystallized form.
use
Copper (II) hydroxide is used as
- Pesticides ( fungicide with special approval in organic fruit, wine, hops, vegetable and banana cultivation)
- for the production of pigments (e.g. Peligot blue , which is lightfast in artificial light)
- for the preparation of the ammoniacal solution known as Schweizer's reagent , which is used as a reagent and for dissolving rayon .
- for the production of copper silk
- for the production of mordants , ship floor paints, catalysts
Admission
Copper (II) hydroxide is approved as a pesticide (trade names Cuprozin , Kocide etc.) in pesticides in many EU countries, including Germany and Austria, as well as Switzerland.
See also
- Fehling's sample (without the addition of potassium sodium tartrate , copper hydroxide would precipitate)
- Copper (I) hydroxide , CuOH
literature
- Georg Brauer: Handbook of preparative inorganic chemistry. ISBN 3-432-26081-4 .
- Pradyot Patnaik: Handbook of Inorganic Chemicals . McGraw-Hill, New York 2002, ISBN 0-07-049439-8 (English)
Individual evidence
- ↑ a b c d e f g h i j Entry on copper (II) hydroxide in the GESTIS substance database of the IFA , accessed on December 30, 2019(JavaScript required) .
- ↑ Entry on Copper dihydroxide in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on December 30, 2019. Manufacturers or distributors can expand the harmonized classification and labeling .
- ↑ uni-bayreuth.de: The color of complex compounds using the example of copper salts , accessed on June 17, 2017.
- ^ AF Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 101st edition. Walter de Gruyter, Berlin 1995, ISBN 3-11-012641-9 , p. 1335.
- ↑ Remy: Textbook of Inorganic Chemistry Volume II. 10th Edition. Akademische Verlagsgesellschaft, Leipzig 1961, p. 455.
- ↑ The Copper Silk Process - Chemical Basics ( Memento from April 20, 2009 in the Internet Archive )
- ↑ General Directorate Health and Food Safety of the European Commission: Entry on Copper hydroxide in the EU pesticide database; Entry in the national registers of plant protection products in Switzerland , Austria and Germany ; accessed on March 13, 2016.