Chlorine dioxide (ClO2) gas is unstable and decomposes, sometimes violently, into Cl2 and O2 (with a 50% increase in gas volume). When storing chlorine dioxide (ClO2), it is commonly kept in CHILLED WATER because its solubility in water significantly increases at lower temperatures, making it more stable and allowing for higher concentrations to be safely stored; essentially, cold water helps to preserve the ClO2 in solution. However, ClO2 is very reactive and breaks down quickly in the presence of sunlight or unchilled water. In water, it reacts to form chlorite ions.
In this process, it is stored as 8 grams per liquid (GPL) in chilled water before use in a pulp-bleaching plant. The decomposition (explosion) is worse as the water temperature rises.