Copper (II) nitrate

Structural formula
General
Surname	Copper (II) nitrate
other names	Copper dinitrate
Molecular formula	Cu (NO 3 ) 2
Brief description	bluish-green, deliquescent crystals; as hydrates deep blue
External identifiers / databases
CAS number 3251-23-8 anhydrous 10031-43-3 trihydrate 13478-38-1 hexahydrate 19004-19-4 hemipentahydrate PubChem 18616 Wikidata Q286064
properties
Molar mass	187.55 g mol −1 (anhydrous) 241.60 g mol −1 (trihydrate)
Physical state	firmly
density	2.05 g cm −3 (trihydrate) 2.07 g cm −3 (hexahydrate)
Melting point	256 ° C (anhydrous salt) 114 ° C (trihydrate) 26 ° C (hexahydrate)
solubility	good in water (1378 g l −1 at 20 ° C)
safety instructions
GHS labeling of hazardous substances danger H and P phrases H: 272-302-315-319-410 P: 210-221-273-302 + 352-305 + 351 + 338
Toxicological data	794 mg kg −1 ( LD 50 ,  rat ,  oral )
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Copper (II) nitrate is a chemical compound of copper from the group of nitrates .

Extraction and presentation

Copper (II) nitrate (trihydrate)

The salt can be obtained very easily in the laboratory by the action of half-concentrated nitric acid on metallic copper. During the reaction, gaseous nitrogen monoxide is formed on the copper , while the color of the solution, analogous to the copper (II) chloride, changes from blue to green with increasing salt concentration .

${\displaystyle \mathrm {3\ Cu+8\ HNO_{3}\longrightarrow 3\ Cu(NO_{3})_{2}+2\ NO+4\ H_{2}O} }$

The resulting colorless nitrogen monoxide reacts immediately with atmospheric oxygen to form red-brown nitrogen dioxide .

${\displaystyle \mathrm {2\ NO+O_{2}\longrightarrow 2\ NO_{2}} }$

Another method is to mix a copper sulfate solution with caustic soda , which creates copper hydroxide . Copper hydroxide dissolves in nitric acid without nitrogen oxides. When saturated, the copper nitrate turns from blue to green to black.

${\displaystyle \mathrm {CuSO_{4}+2\ NaOH\longrightarrow \ Cu(OH)_{2}+Na_{2}SO_{4}} }$

${\displaystyle \mathrm {Cu(OH)_{2}+2\ HNO_{3}\longrightarrow \ Cu(NO_{3})_{2}+2\ H_{2}O} }$

Copper hydroxide is insoluble in water and the sodium sulfate (Glauber's salt) can be washed out.

The reaction of HNO ₃ and Cu (OH) ₂ results in copper (II) nitrate without the formation of nitrogen oxide.

properties

The hydrates are deep blue, the anhydrous substance is blue-green. Solutions of the substance show a color change from blue to dark green with increasing concentration . The crystals slowly melt in the air.

In addition to the hydrates mentioned, copper (II) nitrate can also form a nonahydrate, which is only stable below −20 ° C.

Upon heating of the hydrates is effected no dehydration , rather arises from about 80 ° C basic copper (II) nitrate, at temperatures above 170 ° C Copper (II) oxide .

The substance is hazardous to water ( WGK 2).

use

Copper (II) nitrate is used as tinplate ink, for blackening copper and blackening iron. It is also used for the production of copper oxide , corrosion and wood preservatives, flotation and drilling aids, in the dyeing and dye industry as an oxidizing agent , and for the nitration of organic compounds .

Individual evidence

1. ↑ ^{a b c d e f g h i} Entry on copper (II) nitrate in the GESTIS substance database of the IFA , accessed on January 10, 2017(JavaScript required) .
2. ↑ ^{a b c d} Entry on copper (II) nitrate. In: Römpp Online . Georg Thieme Verlag, accessed on December 28, 2014.