Dichromate salts contain the dichromate anion, . Naphthalene on oxidation with potassium permanganate or potassium dichromate gives phthalic acid. Dichromate and chromate salts are oxidizing agents. The chromate and dichromate ions are fairly strong oxidizing agents. Both methods use acidic chromate or dichromate solutions. The chromate is converted by sulfuric acid into the dichromate. Virtually all chromium ore is processed via hexavalent chromium, specifically the salt sodium dichromate. It is prepared by treating potassium dichromate with potassium hydroxide. Potassium dichromate is usually prepared by the reaction of potassium chloride on sodium dichromate. Potassium dichromate is a strong oxidizing agent under acidic conditions. Approximately of hexavalent chromium, mainly sodium dichromate, were produced in 1985. It is a salt consisting of ammonium ions and dichromate ions. This method used the oxidizing agent potassium dichromate. Oxidation can be achieved by heating the alcohol with an acidified solution of potassium dichromate. This is what happens when concentrated sulfuric acid is added to a dichromate solution.