Chlorine dioxide

Chlorine dioxide is a chemical compound (a thing made when two or more chemical elements attach to each other). Its chemical formula is ClO2. The Cl means 1 chlorine ion and the O2 means two oxide ions. The chlorine is in its +4 oxidation state. That means that when the chemical compound was made, four electrons were taken from the chlorine and given to the oxygens.
Description.
It is a yellowish gas. It has a bad smell. It can explode easily. It reacts (has chemical reactions with) many other chemicals. It explodes when it is more than 15% concentration in air. When light is shined on it, it can explode. It dissolves easily in cold water.
How it is made.
It is made by oxidation (the pulling of electrons away from) of sodium chlorite by chlorine gas.
It can also be made by reduction (giving electrons to) of sodium chlorate in an acidic solution. There are some reducing agents (chemicals that reduce another chemical) that can be used. Methanol (an alcohol), sulfur dioxide (a gas made by burning sulfur), hydrochloric acid (a common acid), or hydrogen peroxide can be used.
There are even more ways to make chlorine dioxide. Sodium chlorite can react with a mixture of sodium hypochlorite and hydrochloric acid to make chlorine dioxide.
Sodium chlorite reacts with hydrochloric acid to make chlorine dioxide.
Electrolysis (the passing of an electric current through a liquid) of a chlorite solution like sodium chlorite makes chlorine dioxide.
Chlorine dioxide can explode easily. That is why it is normally made when it is needed, and immediately dissolved in water to make it safer. It is not normally packaged and sent to people that need it.
Uses.
Chlorine dioxide is used to bleach wood pulp to make paper. It can also be used to disinfect water. There are some ways it is better than chlorine. It is less corrosive (breaking down other things) than chlorine and does not make as many bad things in water.