Mercury(II) nitrate (CAS 10045-94-0): storage and disposal
Mercuric nitrate is a legacy mercury salt found in school, college and university stores, sometimes only as an ingredient in old preparations such as Millon's reagent. It is classified as fatal if swallowed, in contact with skin or if inhaled, and very toxic to aquatic life, with organ damage from repeated exposure. It also oxidises and absorbs moisture, so the state of the solid and what it has been kept beside decide how it is handled.
- CAS number
- 10045-94-0
- Form
- Solid
- Storage class
- Toxic
- Signal word
- Danger
- Usual EWC code
- 16 05 06*
Acute toxicity
Serious health hazard
Hazardous to the environment
What to do this week
- Check the label is readable and write down the opened date if it is not already there.
- Check it is stored as toxic stock and apart from the items listed under "Do not store with".
- If you no longer need it, add it to your disposal list so it goes on the next collection.
Safe storage in a school or lab
Fatal classifications by mouth, skin and inhalation decide the location: a locked toxic cabinet with a stock record, well away from food and drink areas. A second property complicates that choice. As an oxidising salt it is a poor neighbour for organic stock, so check what else lives in that cabinet and keep it clear of solvents, paper and cardboard packaging. Acids and other oxidisers belong elsewhere as well. It also draws moisture from the air, which means a loose cap soon shows in the jar, and a dry spot matters more here than for most mercury salts. Old bottles of Millon's reagent are liquids and leak differently from a jar of crystals, so give them a tray of their own and a label that names the mercury.
How to tell it has deteriorated
Moisture is what changes this salt. It absorbs water from the air, so a once free flowing solid cakes, looks damp or settles into a wet mass at the bottom of the jar. Water also pushes it towards yellowish basic salts, and a yellow tinge on old crystals is consistent with that. Because it oxidises, look for an attacked paper label and for corrosion on a metal cap. Reagent bottles are harder to judge: an old bottle of Millon's reagent may carry only a faded handwritten name, and the label can be the real fault. None of these changes reduces the mercury content. Leave the container shut, and write down what shows from outside it.
How it must be disposed of
By specialist collection only. It never goes down the drain or into general waste. It is normally packed in a toxic laboratory pack with compatible chemicals.
Write down the exact label wording before asking for a collection, along with the jar size, the closure type and whether the contents look dry, caked or wet. A bottle named only as Millon's reagent should be listed under that name with mercury mentioned beside it, since the reagent name hides the hazard from anyone reading a list. Those details set the grouping: it is a mercury salt that also oxidises, so it cannot be packed alongside organic material. Specialist collection is its only exit. A sink, drain, general waste bin or skip is never an option, and nobody should attempt to treat the salt beforehand. In a lab pack it travels under 16 05 06*, with a hazardous waste consignment note.
| EWC code, laboratory chemicals | 16 05 06* |
|---|---|
| Discarded inorganic chemical, not a laboratory pack | 16 05 07* |
| Hazardous waste | Yes |
The code depends on where the waste came from and what it is mixed with. Use the waste code finder to see why.
Do not store with
- OxidiserToxic and oxidising stock are stored apart. A reaction could release toxic vapours.
- AcidToxic stock is stored apart from acids. Several toxic salts release toxic gas in contact with acid.
Named chemicals to keep apart
- Acetic acidToxic stock is stored apart from acids. Several toxic salts release toxic gas in contact with acid.
- Calcium hypochloriteToxic and oxidising stock are stored apart. A reaction could release toxic vapours.
- Hydrochloric acidToxic stock is stored apart from acids. Several toxic salts release toxic gas in contact with acid.
- Hydrogen peroxideToxic and oxidising stock are stored apart. A reaction could release toxic vapours.
- Nitric acidToxic stock is stored apart from acids. Several toxic salts release toxic gas in contact with acid.
- Potassium nitrateToxic and oxidising stock are stored apart. A reaction could release toxic vapours.
- Potassium permanganateToxic and oxidising stock are stored apart. A reaction could release toxic vapours.
- Sulfuric acidToxic stock is stored apart from acids. Several toxic salts release toxic gas in contact with acid.
Common quantities we collect
Usually held as: legacy stock.
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.
Where it is commonly held
Hazard statements
- H300 Fatal if swallowed.
- H310 Fatal in contact with skin.
- H330 Fatal if inhaled.
- H373 May cause damage to organs through prolonged or repeated exposure.
- H410 Very toxic to aquatic life with long lasting effects.
Substance as classified, dilutions may differ.
Questions
We have an old bottle of Millon's reagent. Does it count as mercury(II) nitrate waste?
It contains the salt, so describe it as Millon's reagent containing mercury and not as mercury(II) nitrate alone. An old solution may be less hazardous than the pure solid, but it is not safe, and it stays a mercury waste for specialist collection.
Can it share the locked cabinet with our other mercury compounds?
A locked toxic cabinet suits it, but look at the neighbours first. Because it oxidises, it should sit away from organic compounds and paper, including any organic mercury preservatives. A separate labelled tray on a lower shelf keeps a leak or spill from reaching them.
The crystals in our jar have turned damp and stuck together. Is that serious?
Taking up moisture is normal for this salt, so caking is expected and is no sign of sudden danger. It is also no sign the hazard has eased. Keep the cap on, do not scrape or break up the mass, and mention the condition when arranging collection.