Copper(II) chlorate is a chemical compound of the transition metal

copper Copper is a chemical element; it has symbol Cu (from Latin ) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orang ...

and the

chlorate Chlorate is the common name of the anion, whose chlorine atom is in the +5 oxidation state. The term can also refer to chemical compounds containing this anion, with Chlorate#Compounds (salts), chlorates being the salt (chemistry), salts of chlo ...

anion with basic formula Cu(ClO₃)₂. Copper chlorate is an oxidiser. It commonly forms the tetrahydrate, Cu(ClO₃)₂·4H₂O.

Production

Copper chlorate can be made by combining a hot one molar solution of

copper sulfate Copper sulfate may refer to: * Copper(II) sulfate, CuSO4, a common, greenish blue compound used as a fungicide and herbicide * Copper(I) sulfate, Cu2SO4, an unstable white solid which is uncommonly used {{chemistry index Copper compounds ...

, with

barium chlorate Barium chlorate, Ba(ClO3)2, is the barium salt of chloric acid. It is a white crystalline solid, and like all soluble barium compounds, irritant and toxic. It is sometimes used in pyrotechnics to produce a green colour. It also finds use in t ...

, which results in the precipitation of

barium sulfate Barium sulfate (or sulphate) is the inorganic compound with the chemical formula Ba SO4. It is a white crystalline solid that is odorless and insoluble in water. It occurs in nature as the mineral barite, which is the main commercial source of ...

. When the solution is filtered, cooled and evaporated under a vacuum blue crystals form. :CuSO₄ + Ba(ClO₃)₂ → Cu(ClO₃)₂ + BaSO₄(s)

Properties

In 1902, A. Meusser investigated solubility of copper chlorate and found that it melted and started decomposing above 73 °C, giving off

chlorine Chlorine is a chemical element; it has Symbol (chemistry), symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between ...

. Copper chlorate decomposes when heated, giving off a yellow gas, which contains chlorine, oxygen and

chlorine dioxide Chlorine dioxide is a chemical compound with the formula ClO2 that exists as yellowish-green gas above 11 °C, a reddish-brown liquid between 11 °C and −59 °C, and as bright orange crystals below −59 °C. It is usually ...

. A green solid is left that is a basic copper salt. :2 Cu(ClO₃)₂ → 2 CuO + Cl₂ + 3 O₂ + 2 ClO₂ Sulfur is highly reactive with copper chlorate, and it is important not to cross contaminate these chemicals, for example in pyrotechnic making.

Structure

Copper(II) chlorate commonly crystallizes as a tetrahydrate, though a hexahydrate is also known. Tetraaquacopper(II) chlorate, Cu(ClO₃)₂·4H₂O, has an

orthorhombic In crystallography, the orthorhombic crystal system is one of the 7 crystal systems. Orthorhombic Lattice (group), lattices result from stretching a cubic crystal system, cubic lattice along two of its orthogonal pairs by two different factors, res ...

crystal structure. Each copper atom is octahedrally coordinated, surrounded by four oxygen atoms of water, and two oxygen atoms from chlorate groups, which are opposite each other. Water is closer to the copper than chlorate, 1.944 Å compared to 2.396 Å, exhibiting the Jahn-Teller effect. The chlorate groups take the shape of a distorted tetrahedron. At , the chlorine-oxygen distances in each chlorate ion are 1.498, 1.488 and 1.468 Å, with the longest being the oxygen next to copper. The ∠O-Cu-O (angle subtended at copper by oxygen atoms) is 105.2°, 108.3°, and 106.8°. At lower temperatures (), the water molecules and copper-chlorate distance shrink.

Use

François-Marie Chertier used tetraamminecopper(II) chlorate to colour flames blue in 1843. This material was abbreviated TACC with formula Cu(NH₃)₄(ClO₃)₂. TACC explodes on impact. The substance became known as Chertier's copper for use in blue coloured pyrotechnics. However its deliquescence causes a problem. Mixtures with other metal salts can yield violet or lilac colours also. It has also been used to colour copper brown.

References

{{Chlorates Chlorates Copper(II) compounds