Copper(II) chloride

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Copper(II) chloride
Copper(II) chloride anhydrous by Zyklon-A.png
Anhydrous copper (II) chloride
CuCl2 Dihydrate.jpg
Pieces of copper(II) chloride dihydrate
Names
IUPAC name
Copper(II) chloride
Other names
Copper dichloride
Cupric chloride
Cupric dichloride
Properties
CuCl2 (anhydrous)
CuCl2·2H2O (dihydrate)
Molar mass 134.45 g/mol (anhydrous)
170.48 g/mol (dihydrate)
Appearance Brown solid (anhydrous)
Blue-green solid (dihydrate)
Odor Odorless
Density 3.386 g/cm3 (anhydrous)
2.51 g/cm3 (dihydrate)
Melting point anhydrous
498 °C (928 °F; 771 K)
dihydrate
100 °C (212 °F; 373 K) (dehydrates)
Boiling point 993 °C (1,819 °F; 1,266 K) (anhydrous, decomposes)
70.6 g/100 mL (0 °C)
75.7 g/100 mL (25 °C)
107.9 g/100 mL (100 °C)
Solubility Soluble in acetone
Solubility in ethanol 53 g/100 mL (15 °C)
Solubility in methanol 68 g/100 mL (15 °C)
Hazards
Safety data sheet Sigma-Aldrich (anhydrous)
Sigma-Aldrich (dihydrate)
Flash point Non-flammable
Related compounds
Related compounds
Copper(I) chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Copper(II) chloride, also known as cupric chloride, is an ionic compound of copper and chlorine with the formula CuCl2. It is a brown solid when anhydrous, but turns a brilliant turquoise color when hydrated.

Properties

Physical properties

Still-wet CuCl2 crystals grown on the inside of a beaker.

Copper(II) chloride is a brown powder that turns red when molten. Its melting point is 498 °C. Copper(II) chloride is hygroscopic and absorbs water in open air to form the dihydrate, which is a neutral tetracoordinate complex. The material normally exists as a brilliant turquoise powder, but thin, transparent, fragile crystals may be grown. In the presense of excess chloride ions, it will form a greener colored acidic copper(II) chloride, in which the water ligands are substituted for chloride ions. Tetrachlorocupric acid is formed.

Chemical properties

Copper(II) chloride can oxidize and dissolve aluminium, owing to the formation of the tetrachlorocuprate ion. Besides this, it is a moderate oxidizer and will also dissolve other reactive metals such as zinc and magnesium. It is also useful in organic synthesis because it can chlorinate the alpha position of carbonyls. In the presence of oxygen, it can also oxidize phenols.

Copper(II) chloride burns at low temperature with a deep blue flame (or green, depending on impurities). If the flame temperature is too high, it breaks down and gives a more greenish flame color. For this reason, it cannot be used in fireworks to obtain blue flame.

Availability

Copper chloride can be purchased from chemical suppliers or online from eBay and Amazon. ScienceCompany sells 100 g of copper(II) chloride dihydrate at 11.95$.

Preparation

Copper(II) chloride can be produced by adding copper metal to a mixture of hydrochloric acid and hydrogen peroxide. Copper is resistant to attack by pure hydrochloric acid and other non-oxidizing acids, so an oxidizer must be added to promote dissolution (in this case, hydrogen peroxide). Copper(II) oxide or hydroxide can be used instead of copper metal.

Totally anhydrous copper(II) chloride can be made by passing dry chlorine gas over hot copper metal.

Projects

Handling

Safety

Copper(II) chloride is toxic and corrosive, so proper protection, such as gloves should be worn when handling the compound.

Storage

Copper(II) chloride should be stored in closed containers, to keep it dry. The anhydrous form should be kept in sealed containers or in a desiccator.

Disposal

Copper(II) chloride must be reduced to copper metal with with another more reactive metal, such as iron or zinc to form iron(II) chloride or zinc chloride which are less toxic, before being disposed of.

References

Relevant Sciencemadness threads