Calcium chlorate

Calcium chlorate is the calcium salt of chloric acid, with the chemical formula Ca(ClO₃)₂. Like other chlorates, it is a strong oxidizer.

Calcium chlorate

Identifiers
CAS Number	10137-74-3 Y
3D model (JSmol)	Interactive image
ChemSpider	23349 Y
ECHA InfoCard	100.030.331
EC Number	233-378-2
PubChem CID	24978
RTECS number	FN9800000
UNII	2R958OYG8P N
CompTox Dashboard (EPA)	DTXSID70894195
InChI InChI=1S/Ca.2ClHO3/c;2*2-1(3)4/h;2*(H,2,3,4)/q+2;;/p-2 Y Key: YALMXYPQBUJUME-UHFFFAOYSA-L Y InChI=1/Ca.2ClHO3/c;2*2-1(3)4/h;2*(H,2,3,4)/q+2;;/p-2 Key: YALMXYPQBUJUME-NUQVWONBAM
SMILES [Ca+2].[O-]Cl(=O)=O.[O-]Cl(=O)=O
Properties
Chemical formula	Ca(ClO3)2
Molar mass	206.98 g/mol
Appearance	white solid deliquescent
Odor	odorless
Density	2.71 g/cm3
Melting point	150°C (dihydrate, decomp) 325°C
Solubility in water	209 g/100mL (20 °C) 197 g/100mL (25 °C)
Structure
Crystal structure	monoclinic
Hazards
NFPA 704 (fire diamond)	1 0 1 OX
Related compounds
Other anions	calcium chloride calcium bromate calcium bromide
Other cations	potassium chlorate sodium chlorate barium chlorate magnesium chlorate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Production

Calcium chlorate is produced by passing chlorine gas through a hot suspension of calcium hydroxide in water, producing calcium hypochlorite, which disproportionates when heated with excess chlorine to give calcium chlorate and calcium chloride:^[1]

6 Ca(OH)₂ + 6 Cl₂ → Ca(ClO₃)₂ + 5 CaCl₂ + 6 H₂O

This is also the first step of the Liebig process for the manufacture of potassium chlorate.^{[citation needed]}

In theory, electrolysis of hot calcium chloride solution will produce the chlorate salt,^{[citation needed]} analogous to the process used for the manufacture of sodium chlorate. In practice, electrolysis is complicated by calcium hydroxide depositing on the cathode, preventing the flow of current.

Reactions

When concentrated solutions of calcium chlorate and potassium chloride are combined, potassium chlorate precipitates:^[1][2]

Ca(ClO₃)₂ + 2 KCl → 2 KClO₃ + CaCl₂

This is the second step of the Liebig process for the manufacture of potassium chlorate.^[2]

Solutions of calcium chlorate react with solutions of alkali carbonates to give a precipitate of calcium carbonate and the alkali chlorate in solution:

Ca(ClO₃)₂ + Na₂CO₃ → 2 NaClO₃ + CaCO₃

On strong heating, calcium chlorate decomposes to give oxygen and calcium chloride:

Ca(ClO₃)₂ → CaCl₂ + 3 O₂

Cold, dilute solutions of calcium chlorate and sulfuric acid react to give a precipitate of calcium sulfate and chloric acid in solution:^[3]

Ca(ClO₃)₂ + H₂SO₄ → 2 HClO₃ + CaSO₄

Contact with strong sulfuric acid can result in explosions^[4] due to the instability of concentrated chloric acid. Contact with ammonium compounds can also cause violent decomposition due to the formation of unstable ammonium chlorate.^[4]

Uses

Calcium chlorate has been used as an herbicide,^{[citation needed]} like sodium chlorate.

Calcium chlorate is occasionally used in pyrotechnics,^{[citation needed]} as an oxidizer and pink flame colorant. Its hygroscopic nature and incompatibility with other common pyrotechnic materials (such as sulfur) limit its utility in these applications.

References

1. Samuel P. Sadtler, Virgil Coblentz and Jeannot Hostmann (1918). A textbook of chemistry, intended for the use of pharmaceutical and medical students. p. 329.
2. Mellor, Joseph William (1917). Modern Inorganic Chemistry. p. 287.
3. Ira Remsen, Charles August Rouillu (1883). "American Chemical Journal". 4: 309. Solution of pure calcium chlorate, treated by sulphuric acid, would of course give a solution of chloric acid {{cite journal}}: Cite journal requires |journal= (help)
4. PubChem - Calcium Chlorate: Experimental Properties