Potassium superoxide (CAS 12030-88-5): storage and disposal

Water and organic matter must stay away from it, because it reacts violently with the first and can explode with the second. On a real shelf, organic matter means more than solvent bottles. Grease on a ground glass stopper, a rubber bung, a plastic scoop left in the jar and a cardboard outer box all count, along with skin oils from a gloved hand that has handled something else. A dry, separate oxidiser space on non-combustible shelving is the place for it, well away from flammable, acid and alkali stock. Where a supplier sealed it under dry gas, that seal is doing most of the work. If the jar is already old, damaged or of unknown history, leave it there and do not open it.

Check first for a damaged seal, a damp lid or a label that has stained or lifted. A swollen container suggests oxygen has been released, because the solid gives off oxygen when it meets water. Next look at the colour through the glass. Sound stock is a yellow to orange solid. Moisture and carbon dioxide from the air turn the outer part white as it converts to potassium hydroxide and carbonate, so a pale crust shows that air has been getting in, while the core may still be fully reactive. Corroded caps and marks on the shelf point the same way. Anything organic on or around the jar is a serious finding. Do not open it, tap it or try to break up a crust.

This does not go through our standard collection route. It is arranged by manual enquiry, and never goes down the drain or into general waste.

Nobody should add water, wipe the jar with a damp cloth or try to make this safe, and it must never go into a sink, a drain, a bin or a skip. Those are the mistakes that turn a stored chemical into a fire. It is not quoted online and the online quote path does not accept it, so send a manual enquiry. A store assessment is recommended, with a competent chemist seeing it in person. An explosives or emergency specialist may be needed where warning signs exist. Say what the label reads, whether the seal is intact, whether you can see white crust and what stands next to it. Do not open or move it in the meantime. University stock normally takes code 16 05 06*.

Usually held as: solid.

Tell us the container size and how many you hold. An estimate is enough to start with, and some items cannot be priced until someone has looked at them.