Potassium dichromate

Potassium dichromate is a chemical compound. It contains potassium and dichromate ions. It has a chemical formula of K2Cr2O7 (K2Cr). The chromium is in its +6 oxidation state.
Properties.
It is a bright red crystalline solid. It is a strong oxidizing agent in acidic conditions. It is poisonous because it contains dichromate, which is carcinogenic. It can be destroyed by reaction with reducing agents. It can be reduced to green chromium(III) compounds such as chromium(III) oxide. 
Preparation.
Potassium dichromate can be made by oxidation of potassium hydroxide and chromium(III) oxide. It can also be made by adding an acid to potassium chromate. 
Occurrence.
It is very rarely found in the earth. It is only found in very dry areas. If it rains, it dissolves in the water and is washed away.
Uses.
It is used as a reagent for many chemicals, such as alcohol. Some breath alcohol testers use this, and the red turns to green when there is alcohol in the breath. It can be used to make chromic acid, which is used to clean glass. It can be used in cement. It is used to tan leather. It can be used in photography and to test for certain metals. It can be used to treat wood.
Safety.
Potassium dichromate is very irritating. It can cause cancer when the dust is inhaled. It is a strong oxidizing agent and can start fires. It can be reacted with iron(II) sulfate to detoxify (remove the toxicity of) it.