What is a solvent in copper sulfate

Copper sulfate

Crystal structure
__Cu2+ __S __O
General
Surname Copper (II) sulfate
other names
  • Copper (II) sulphate (VI)
  • Blue vitriol
  • blue Galitzenstein
  • Bluestone
Ratio formula CuSO4
CAS number
  • 7758-98-7
  • 7758-99-8 (pentahydrate)
  • 10257-54-2 (monohydrate)
ATC code

V03AB20

Brief description

white to gray, odorless powder[1]
Hydrates: light blue to slightly turquoise crystals

properties
Molar mass 159.61 g mol−1
249.69 g mol−1 (Pentahydrate)
Physical state

firmly

density

3.60 g cm−3
2.284 g · cm−3 (Pentahydrate, 25 ° C)[1]

Melting point

Decomposes at 560 ° C[1]

solubility

Easily soluble in water: 203 g · l−1 (20 ° C)[1]

safety instructions
MAK

0.1 mg m−3 (measured as an inhalable aerosol part)[1]

As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions.
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Copper sulfate, earlier too Blue vitriol (see Vitriole), is the copper salt of sulfuric acid and consists of Cu2+-Cations and SO42−-Anions. It is a colorless, non-flammable solid that is very soluble in water. Water-containing copper sulfates (hydrates), for example copper (II) sulfate pentahydrate, are blue in color.

Occurrence

CuSO4 · 5 H2O crystal

Copper sulphate occurs naturally as a weathering product of sulphidic copper ores as crust-shaped, granular or fibrous aggregates. The anhydrous form (CuSO4) does not occur in nature, but only copper sulfate pentahydrate (CuSO4 · 5 H2O) as a rare mineral chalkanthite. Due to the very good water solubility of copper sulfate, however, it is only preserved in very dry climates and is therefore only found in deserts such as the Atacama (Chile).

Extraction and presentation

In the laboratory, for example, copper sulfate can be produced from copper hydroxide and sulfuric acid:

$ \ mathrm {\ Cu (OH) _2 + H_2SO_4 \ longrightarrow} $$ \ mathrm {\ CuSO_4 + 2 \ H_2O} $

Technically, copper sulfate is obtained through the action of sulfuric acid on copper oxides or copper sulfides.

$ \ mathrm {\ CuO + H_2SO_4 \ longrightarrow} $$ \ mathrm {\ CuSO_4 + H_2O} $
$ \ mathrm {\ CuS + H_2SO_4 \ longrightarrow} $$ \ mathrm {\ CuSO_4 + H_2S} $

Copper sulfate is by far the most important copper salt.

properties

Copper sulfate is good in water, not soluble in most organic solvents. It dissolves in glycerine with an emerald green color. With strong heating (from 340 ° C) the anhydrous copper sulfate breaks down into copper (II) oxide and sulfur trioxide.

Hydrates

In addition to the anhydrous compound, copper (II) sulfate hydrates containing water of crystallization also occur. The most common is the pentahydrate (CuSO4 · 5 H2O). There is also a trihydrate (CuSO4 · 3 H2O) and copper (II) sulfate monohydrate (CuSO4 · H2O). Below are the properties of the hydrates that differ from those of the anhydrous compound, if available.

Copper (II) sulfate pentahydrate

Loss of water of crystallization with CuSO4 · 5 H2O (TGA / DTA)

Copper sulfate pentahydrate CuSO4 · 5 H2O (copper (II) tetraoxosulfate (VI) pentahydrate, mineral name: chalcanthite) forms triclinic crystals with a blue color, which gradually give off their water of crystallization when heated and finally become colorless copper sulfate anhydrate. At 95 ° C, two water molecules split off, creating the trihydrate. Another two water molecules are split off at 116 ° C, the last one at 200 ° C, the crystals lose their blue color and become colorless copper sulfate CuSO4. This process is reversible, when the anhydrate is dissolved in water, the solution is colored by hydration of the Cu2+-Ions blue and heats up (hydration energy). The blue copper sulfate pentahydrate can crystallize again from the solution through evaporation of the water. The chemical formula of the pentahydrate should better be according to [Cu (H2O)4]SO4 · H2O, because in the crystal structure four water molecules are coordinated directly to the copper (II) ions and surround them in a square-planar manner.

  • Brief description: blue, odorless solid
  • Release of water of crystallization: 88–245 ° C
  • thermal decomposition: 340-650 ° C
  • Solubility: easily soluble in water: 317 g / l

use

Copper sulfate is used for a large number of processes and reactions, for example for copper plating, for the production of copper-containing paints, for etching, in medicine as an astringent (astringent) agent, and in the past also as an emetic (it tastes unpleasantly bitter, but is not to be regarded as non-toxic ), in New Year's rockets (creates a bluish-green hue) and other applications.

Electroplating

Copper sulphate is used for galvanic copper plating in electroplating and in the form of Oettel's solution in coulometry to determine the exact amount of charge.

Labelling

Copper sulphate is also found as an additive in marking paints, which is painted on a metallic surface before marking in order to make the actual crack more visible after marking.

Plant protection

Copper sulphate solution mixed with calcium hydroxide suspension was previously used as Bordeaux broth in viticulture to combat fungal diseases. Today pesticides are used that contain copper sulfate or other copper compounds. Modern, copper-containing pesticides are better formulated and have lower concentrations of copper sulfate, copper oxychloride, copper hydroxide or copper octanoate. Because of possible soil pollution with copper salts, alternatives are being sought (e.g. phosphonates).

Integrated viticulture and organic viticulture have limited the number of applications of copper-containing products. However, in organic viticulture, copper-containing agents are of central importance in combating downy mildew.

Desiccant

Dry copper sulfate (white) and in the middle after adding water: copper sulfate pentahydrate (light blue)

The anhydrous, white copper sulphate serves as a drying agent (for example for the production of anhydrous ethanol) and for the detection of water, whereby it turns blue due to the storage of crystal water.

Crystal growing

Copper sulfate is very popular for growing crystals, especially at school.

Swimming pools

In combination with ammonium sulfate, copper sulfate is used against algae in swimming pools. The copper sulphate in no way discolors the water, but copper sulphate can cause hair to turn green.

medicine

The paramagnetic property of copper sulfate makes it possible to use it as a contrast agent in magnetic resonance spectroscopy (NMR). In the German Pharmacopoeia, anhydrous copper (II) sulfate is monographed, in the European Pharmacopoeia copper (II) sulfate pentahydrate. Copper sulfate was previously used externally as a caustic agent, as astringency and in wound treatment, internally as an emetic, to stop bleeding and as an antidote to phosphorus poisoning. In sheep farming and veterinary medicine, copper sulphate is used to treat the mustard leg, a bacterial disease of the claws in sheep.

Biological importance

Copper sulfate is very toxic to living organisms and has harmful effects in the aquatic environment. The water-polluting salt is classified in water hazard class 2.

safety instructions

Contact with strong reducing agents (e.g. finely powdered magnesium) or hydroxylamine can lead to dangerous reactions with strong heat generation.

Individual evidence

  1. 1,01,11,21,31,41,5Entry to Copper sulfate in the GESTIS substance database of the IFA, accessed on March 8th. 2008 (JavaScript required).
  2. 2,02,1Entry from the CLP regulation too CAS no. 7758-98-7 in the GESTIS substance database of the IFA (JavaScript required)
  3. ↑ Since December 1, 2012, only GHS hazardous substance labeling has been permitted for substances. Until June 1, 2015, the R-phrases of this substance can still be used to classify preparations, after which the EU hazardous substance labeling is of purely historical interest.

literature

Web links

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