Chlorate

Chlorate is a chemical anion containing one chlorine atom and three oxygen atoms. In this specific arrangement, the chlorine atom exists in a +5 oxidation state. This term can also describe chemical compounds known as salts of chloric acid. These substances are important because they act as powerful oxidizers. An oxidizer is a substance that enables or accelerates the burning of other materials. Because of this strength, chlorates must be kept away from organic materials.

The physical shape of a chlorate anion is quite specific. According to valence shell electron pair repulsion theory, it has a trigonal pyramidal structure. This means the atoms are arranged like a three-sided pyramid. The bonds between the chlorine and oxygen atoms are also unique. In potassium chlorate, all Cl–O bonds have a length of 1.49 Å. Because the chlorine atom is hypervalent, one single Lewis structure cannot represent it perfectly. Instead, scientists view it as a resonance hybrid of multiple structures.

Chlorates are highly reactive when they meet combustible materials. They can react with sugar, sawdust, charcoal, metals, or organic solvents. When these mixtures meet, they will readily deflagrate. Deflagration is a type of rapid burning. Because of this reactivity, chlorates were once widely used in pyrotechnics. However, their use has fallen because they are quite unstable. Most modern pyrotechnic applications now use perchlorates instead. Perchlorates are more stable than the chlorates they replaced.

There are several ways to produce chlorates in a controlled setting. In a laboratory, metal chlorates can be made by adding chlorine to hot metal hydroxides like KOH. This process involves a reaction called disproportionation. During disproportionation, the chlorine undergoes both reduction and oxidation at once. The chlorine starts with an oxidation number of 0. It then forms chloride, which has an oxidation number of -1. Simultaneously, it forms chlorate(V), which has an oxidation number of +5. If the metal hydroxides are cold and aqueous, a different result occurs. This produces chloride and hypochlorite instead of chlorate.

Industrial production follows a different path to create sodium chlorate. Factories start with an aqueous sodium chloride solution, which is called brine. They do not use chlorine gas directly like a lab might. Instead, they use electrolysis to drive the chemical change. If the equipment allows chlorine and sodium hydroxide to mix, disproportionation occurs. The electrical power used for electrolysis also provides necessary heat. This heating keeps the reactants between 50 and 70 °C.

Nature also contains chlorate in several surprising locations. A 2010 study discovered natural chlorate deposits around the world. These are found in high concentrations in arid and hyper-arid regions. Chlorate has also been measured in samples of rainfall. The amount found in rain is similar to the amount of perchlorate. Scientists believe chlorate and perchlorate may share a common natural formation mechanism. This suggests they are part of the chlorine biogeochemistry cycle.

Microorganisms play a significant role in the life of chlorate. Many microbes are capable of reducing chlorate into chloride. This process might be an ancient biological phenomenon. All perchlorate-reducing bacteria described so far also use chlorate as a terminal electron acceptor. This means they use chlorate to help complete biological processes. While chlorate is important, no chlorate-dominant minerals are currently known. The anion usually exists as a substitution in other minerals or in pore-filling solutions.

We can categorize various oxyanions of chlorine by their oxidation states. Using a specific naming convention, one can use Roman numerals to identify them. For example, hypochlorite is called chlorate(I) with a +1 state. Chlorite is chlorate(III) with a +3 state. The standard chlorate is chlorate(V) with a +5 state. Finally, perchlorate is chlorate(VII) with a +7 state. Common chlorate salts include potassium chlorate, sodium chlorate, and magnesium chlorate. While chlorates are relatively toxic, they generally form harmless chlorides when they undergo reduction.

Space exploration has also revealed the presence of these chemicals. In 2011, a study from the Georgia Institute of Technology found something amazing. They unveiled the presence of magnesium chlorate on the planet Mars. This discovery shows that these chemical processes are not limited to Earth. Understanding chlorates helps scientists learn about the chemistry of different worlds. It also helps us understand how elements move through different environments.