Chromium(III) chloride (CAS 10025-73-7): storage and disposal

Check the neighbours before the lid. In a typical prep room this jar stands among other chromium compounds, and green chromium salts are easy to confuse with one another and with nickel or copper salts of a similar colour. Label it by full name and form, and keep it away from stock whose classification differs sharply. A dry general shelf is enough, since it needs no fire cabinet, but because it can cause an allergic skin reaction, handling with a clean spatula and not bare hands is sensible. The salt picks up moisture, so keep the cap tight and the jar on a tray, with the date received on the label.

Look for stickiness. Hydrated chromium chloride crystals can draw in water and clump, then leave a green wet film at the base of the jar and a damp ring on the shelf. A crust at the neck, a corroded cap and a label that has lifted with damp tell the same story. Colour is a poor guide because the salt is dark green whether fresh or old, though a jar that has gone paler or patchy on the surface has been exposed. This salt gives few dramatic signs with age, so the label, the date and the stock record carry most of the information.

By specialist collection only. It never goes down the drain or into general waste. It is normally packed in a non-regulated or low hazard laboratory pack with compatible chemicals.

How it leaves the site is simple but must be accurate. It is a hazardous waste, so the stock is described as chromium(III) chloride hexahydrate, not as a general chromium salt, to avoid confusion with other chromium compounds. A laboratory pack uses 16 05 06* and discarded inorganic stock outside one uses 16 05 07*. Leftover solutions from practical work are bottled and described separately with an approximate volume. Neither the solid nor a solution may go into a sink or the ordinary bin because of the aquatic classification. Keep the original jar if it seals, and request a specialist collection.

Usually held as: hexahydrate.

Part-used bottles and full containers are both fine. Tell us the size and how many, and an estimate is enough for a first price.