Calcium chlorate

Description

Calcium chlorate forms white to yellow deliquescent crystals. Molecular weight=243; Specific gravity(H2O:1)=2.71; Freezing/Melting point=340°(loses H2Oof crystallization at .100°). Hazard Identification (basedon NFPA-704 M Rating System): Health 1, Flammability 0,Reactivity 0; oxidizer. Highly soluble in water.

Chemical properties

Calcium chlorate forms white to yellow deliquescent crystals.

Physical properties

Calcium chlorate Ca(ClO3)2 is the chemical compound formed from calcium and the chlorate anion. Like KClO3, it is a strong oxidizer and can be used in pyrotechnic formulations. Its molecular weight is 206.98 g/mol. Its solubility in water is 209 g/100 ml at 20°C. It is slightly soluble in alcohol. Calcium chlorate has a melting point of 325°C and its density is 2.71 g/cm3. Its CAS number is 10017-74-3. A dihydrate, Ca(ClO3)2·2H2O, forms as white monoclinic crystals, which are decomposed by heating above 150°C. No structural data is available.

The Uses of Calcium chlorate

Calcium chlorate has been used as an herbicide, like sodium chlorate. It is occasionally used in photography, dusting powder to kill poison ivy, pyrotechnics, 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.

Preparation

Calcium chlorate can be prepared by the Liebig process which is also used to prepare the alkali chlorates.
In Liebig’s process, chlorine is passed into milk of lime, at or above a temperature of 1000°C, the apparent reaction being:
6Ca(OH)2＋ 6Cl2→5CaCl2＋ Ca(CIO3)2＋ 6H2O.
But this may comprise two minor reactions:
2Ca (OH)2＋ 2Cl2→CaCl2＋ Ca(OCl)2＋ 2H2O;
3Ca(OCI)2→2CaCl2＋ Ca(CIO3)2
This salt can also be prepared from calcium chloride by an electrochemical method:
CaCl2 (aq)＋ 6H2O (aq)＋ e^-→Ca(ClO3)2＋ 6H2
using a platinum anode and a rotating stainless steel cathode. Yields of the dihydrate up to 78% have been achieved. The hydrogen produced can be “burned” to reform water.

General Description

Calcium chlorate appears as a white crystalline solid. It forms a very flammable mixture with combustible materials and this mixture may be explosive if the combustible material is finely divided. The mixture can be ignited by friction. Contact with strong sulfuric acid can cause fires or explosions. When mixed with ammonium salts, spontaneous decomposition and ignition may result. Prolonged exposure of the material to fire or heat can result in an explosion. Calcium chlorate is used in photography, in pyrotechnics, and as a herbicide.

Air & Water Reactions

Water soluble.

Reactivity Profile

An oxidizing agent. Liberates explosive chlorine dioxide gas in the presence of strong acid. Heating a moist mixture with a dibasic organic acid liberates chlorine dioxide and carbon dioxide. Mixtures with ammonium salts, powdered metals, silicon, sulfur, or sulfides are readily ignited and potentially explosive [Bretherick 1979 p. 806]. A combination with finely divided aluminum can explode by heat, percussion, or friction [Mellor 2:310 1946-47].

Hazard

Oxidizer, dangerous fire risk, forms explo- sive mixtures with combustible materials.

Health Hazard

Inhalation of dust causes irritation of upper respiratory system. Dust irritates eyes and skin. Ingestion causes abdominal pain, nausea, vomiting, diarrhea, pallor, shortness of breath, unconsciousness.

Fire Hazard

Behavior in Fire: When involved in a fire, may cause an explosion. Irritating gases may be generated when heated.

Safety Profile

Moderately toxic by ingestion and intraperitoneal routes. A powerful oxidant. Incompatible with Al, As, C, Cu, charcoal, MnO2, metal sulfides, S, dibasic organic acids, organic matter, P. When heated to decomposition it emits toxic fumes of Cl-. See also CHLORATES for fire, disaster, and explosion hazards.

Potential Exposure

Calcium chlorate is used in making fireworks, herbicides (weed killers) and in photography. Incompatibilities: A strong oxidizer. Reacts, possibly with risk of fire and explosion, with acids (especially organic acids), reducing agents; aluminum, arsenic, chemically active metals; combustible materials; ammonium compounds; charcoal, copper, cyanides; manganese dioxide, metal sulfides; phosphorus, sulfur

First aid

If this chemical gets into the eyes, remove anycontact lenses at once and irrigate immediately for at least15 min, occasionally lifting upper and lower lids. Seekmedical attention immediately. If this chemical contacts theskin, remove contaminated clothing and wash immediatelywith soap and water. Seek medical attention immediately. Ifthis chemical has been inhaled, remove from exposure,begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR ifheart action has stopped. Transfer promptly to a medicalfacility. When this chemical has been swallowed, getmedical attention. Give large quantities of water and inducevomiting. Do not make an unconscious person vomit.Note to physician: Treat for methemoglobinemia.Spectrophotometry may be required for precise determination of levels of methemoglobin in urine.

storage

Color Code—Yellow: Reactive Hazard; Store in alocation separate from other materials, especially flammablesand combustibles. Store in tightly closed containers in a cool,well-ventilated area away from strong acids (such ashydrochloric, sulfuric, and nitric) and chemically active metals(such as potassium, sodium, magnesium and zinc). Calciumchlorate must be stored to avoid contact with organic matter,ammonium compounds, aluminum, copper, cyanides, flammable vapors, and other oxidizable materials since violent reactions occur. Avoid storage on wood floors. Friction, heat, orphysical shocks may cause calcium chlorate to ignite andexplode. Wherever calcium chlorate is used, handled, manufactured, or stored, use explosion-proof electrical equipmentand fittings. See OSHA Standard 1910.104 and NFPA 43ACode for the Storage of Liquid and Solid Oxidizers for detailedhandling and storage regulations.

Shipping

UN1452 Calcium chlorate, Hazard Class: 5.1; Labels: 5.1-Oxidizer. UN2429 Calcium chlorate, aqueous solution, Hazard Class: 5.1; Labels: 5.1-Oxidizer

Incompatibilities

Calcium chlorate is used in making fireworks, herbicides (weed killers) and in photography. Incompatibilities: A strong oxidizer. Reacts, possibly with risk of fire and explosion, with acids (especially organic acids), reducing agents; aluminum, arsenic, chemically active metals; combustible materials; ammonium compounds; charcoal, copper, cyanides; manganese dioxide, metal sulfides; phosphorus, sulfur

Waste Disposal

For barium chlorate, the UN recommends using a vast volume of a reducing agent (bisulfites, ferrous salts or hypo) followed by neutralization and flushing to the sewer with abundant water. This should be applicable here as well.