mercury forms chemical compounds in 2 oxidation states: +1 and +2. mercury(i) compounds are weak oxidizing agents and weak reducing agents. most of them are colorless. they easily disproportionate to mercury(ii) compounds and mercury metal. they react with oxygen in the air to make mercury(ii) compounds. many mercury(i) compounds do not dissolve in water. mercury(i) chloride is one of the most common mercury(i) compounds. mercury(ii) compounds are strong oxidizing agents and very corrosive. mercury(ii) compounds are red, yellow, or colorless. mercury(ii) oxide and mercury(ii) chloride are the most common mercury(ii) compounds in the laboratory.