Mercury(II) sulfate (CAS 7783-35-9): storage and disposal
Mercuric sulfate is a white mercury salt held as legacy stock in school, college and university stores, and it has long been a reagent in water analysis. Classified as fatal if swallowed, in contact with skin or if inhaled, it may damage organs through repeated exposure and is very toxic to aquatic life. Moisture is the property that matters on the shelf, since water turns the white solid into a yellow basic salt.
- CAS number
- 7783-35-9
- 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
A fatal rating by mouth, skin and inhalation puts this salt behind a lock, on a stock record, far from food and drink areas. Fine white powder is the everyday concern, because it looks much like the ordinary salts around it, so a legible label matters as much as the cabinet. Older labels may read mercuric sulfate. The other deciding factor is damp. Water breaks the salt down and frees sulfuric acid, so a humid corner or a shelf beside wet benches is a bad choice, and a metal cap on a damp jar will not last. Acids and oxidisers are kept in other stores. Renew a failing label while the wording can still be read, and keep the jar on a tray that shows any spilled powder.
How to tell it has deteriorated
Sound stock is a white crystalline powder, usually loose. Yellow is the colour to notice, because moisture converts this salt to a yellow basic sulfate. A yellow skin near the cap or down one side of the jar suggests the seal has let damp in, and a whole jar gone yellow has probably been wet for some time. Since the same reaction frees acid, a corroded cap or an attacked label often comes with it. Beyond this the salt shows little. Caking and a failed seal are the other things to record, along with any gap in the stock record. The colour change does not make the contents less hazardous, and nobody needs to open the jar to confirm 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.
List of Waste code 16 05 06* is the entry when this salt leaves in a lab pack, and the asterisk records that it is hazardous waste, so a consignment note will be needed. For the request, give the name on the label, the amount and the colour of the contents, since a yellowed jar has changed and may have an acidic residue about the closure. Tubes and kits from old water analysis work may hold it as well, and these should be listed by what the kit says. Specialist collection is the single route for all of it. Do not send it down a sink or drain or put it in a bin or skip, and do not attempt any treatment ahead of the visit.
| 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.
Precautionary statements
- P260 Do not breathe dust, fume, gas, mist, vapours or spray.
- P262 Do not get in eyes, on skin, or on clothing.
- P264 Wash hands and exposed skin thoroughly after handling.
- P270 Do not eat, drink or smoke when using this product.
- P271 Use only outdoors or in a well-ventilated area.
- P273 Avoid release to the environment.
- P280 Wear protective gloves, protective clothing, eye protection and face protection.
- P284 In case of inadequate ventilation wear respiratory protection.
- P301+P316 IF SWALLOWED: Get emergency medical help immediately.
- P302+P352 IF ON SKIN: Wash with plenty of water.
- P304+P340 IF INHALED: Remove person to fresh air and keep comfortable for breathing.
- P316 Get emergency medical help immediately.
- P319 Get medical help if you feel unwell.
- P320 Specific treatment is urgent (see supplemental first aid instruction on this label).
- P321 Specific treatment (see supplemental first aid instruction on this label).
- P330 Rinse mouth.
- P361+P364 Take off immediately all contaminated clothing. And wash it before reuse.
- P391 Collect spillage.
- P403+P233 Store in a well-ventilated place. Keep container tightly closed.
- P405 Store locked up.
- P501 Dispose of contents and container in accordance with local, regional, national and international regulations.
Substance as classified, dilutions may differ.
Questions
Our old water analysis kit lists mercuric sulfate. Does it need the same route?
Yes. A kit or pre-filled tube may be less hazardous than a jar of the pure salt, but it is not safe and still holds mercury. List each kit by its label wording and the number of tubes, and leave the tubes sealed for specialist collection.
Why has our white powder turned yellow?
Water is the usual cause. The salt reacts with moisture to form a yellow basic sulfate and frees some acid, so a yellow jar means a seal or a store has let damp in. It stays a mercury waste. Keep it closed and note the colour.
It seems to be releasing acid. Should it move to the acid cupboard?
No. It stays in the locked toxic store and apart from acids, because the mercury decides where it belongs. Put the jar on a resistant tray if it is not already on one, record the change, and mention the condition when you ask for collection.