Copper(II) chloride is light brown when anhydrous. It is green when hydrated. It is a weak oxidizing agent. It reacts with aluminium foil to make hydrogen, copper(I) oxide, and aluminium chloride. This is used in school demonstrations. It releases chlorine and turns into copper(I) chloride when heated very hot. It reacts with sodium hydroxide to make copper(II) hydroxide. Copper(II) chloride reacts with metals to make metal chlorides and copper. It puts out blue flames if it is heated in a flame. It reacts with sulfur dioxide to make copper(I) chloride. It dissolves in water to make a blue solution. When more chloride is added, it turns green, then yellow.