Copper(II) chlorate is a chemical compound of the transition metal
copper
Copper is a chemical element with the symbol Cu (from la, cuprum) 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 pinkis ...
and the
chlorate anion with basic formula Cu(ClO
3)
2. Copper chlorate is an oxidiser. It commonly forms the tetrahydrate, Cu(ClO
3)
2·4H
2O.
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 compound used as a fungicide and herbicide
* Copper(I) sulfate
Copper(I) sulfate, also known as cuprous sulfate, is an inorganic compound with the chemical formula Cu2 SO4. It ...
, 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 color. It also finds use in the p ...
, which results in the precipitation of
barium sulfate. When the solution is filtered, cooled and evaporated under a vacuum blue crystals form.
:CuSO
4 + Ba(ClO
3)
2 → Cu(ClO
3)
2 + BaSO
4(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 with the 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 them. Chlorine i ...
.
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(ClO
3)
2 → 2 CuO + Cl
2 + 3 O
2 + 2 ClO
2
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(ClO
3)
2·4H
2O, has an
orthorhombic 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(NH
3)
4(ClO
3)
2. TACC explodes on impact.
The substance became known as Chertier's copper for use in blue coloured pyrotechnics. However its
deliquescence
Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption or adsorption from the surrounding environment, which is usually at normal or room temperature. If water molecules become suspended among the substanc ...
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