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Chemical collection and stock control for UK schools, universities and hospitals

Cobalt(II) nitrate (CAS 10141-05-6): storage and disposal

Cobalt(II) nitrate hexahydrate is a red crystalline salt kept in school, college and university stores. It combines an oxidiser classification with the same cobalt warnings as the chloride: may cause cancer by inhalation, sensitisation, suspected genetic damage, may damage fertility and very toxic effects on aquatic life. Two storage families therefore apply at once, and neither is optional.

CAS number
10141-05-6
Form
Solid
Storage class
Oxidiser
Signal word
Danger
Usual EWC code
16 05 06*
  • Oxidising pictogramOxidising
  • Corrosive pictogramCorrosive
  • Harmful or irritant pictogramHarmful or irritant
  • Serious health hazard pictogramSerious health hazard
  • Hazardous to the environment pictogramHazardous to the environment

What to do this week

  1. Check the label is readable and write down the opened date if it is not already there.
  2. Check it is stored as oxidiser stock and apart from the items listed under "Do not store with".
  3. 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

Keep it away from anything it could set alight. As an oxidiser it needs a separate labelled space on non-combustible shelving, away from solvents, paper, wood and other organic stock, and away from acids, alkalis and corrosive stock. The ammonia based stock in a school cupboard is a particular worry. Because it is also a sensitiser and carries cancer and reproductive statements, a locked cupboard with a stock record is the right setting. Avoid cardboard liners and wooden trays beneath the jar. A dedicated spoon prevents cross-contamination with organic matter, and the date received belongs on the label.

How to tell it has deteriorated

Expect deep red crystals that flow freely. Hydrated nitrates draw moisture from the air, so a jar that has been open too long turns damp, then clumps, then sits in a pinkish-red wet layer at the base. Look for staining of the shelf or tray beneath, corrosion of the cap and a label that has been wet. Contamination is a particular worry with an oxidiser, so paper fibres, wood dust or organic debris in the crystals should be recorded and the jar left alone. A cracked jar or a damp, stained cardboard box underneath deserves attention before anything is moved.

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 oxidising laboratory pack with compatible chemicals.

Pack and describe it as an oxidiser first. It is kept apart from organic waste, solvents, acids and ammonia stock in a compatible group, and the paperwork says so. The code is 16 05 06* in a laboratory pack and 16 05 07* for discarded inorganic stock outside one, and UN 1477 is the transport entry. Note whether the crystals are dry or damp and whether any paper, wood or other organic matter is near or inside the jar. It must never be washed into a drain or put in the bin, and nobody should try to react it with another chemical. Request a specialist collection.

Waste codes and transport details for Cobalt(II) nitrate
EWC code, laboratory chemicals16 05 06*
Discarded inorganic chemical, not a laboratory pack16 05 07*
Hazardous wasteYes

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

  • FlammableOxidisers can ignite flammable materials or make a fire far more intense.
  • AcidMany oxidisers release toxic gas or become unstable in contact with acid.
  • AlkaliSome oxidisers react strongly with alkalis, and ammonia based stock is especially at risk.
  • ToxicToxic and oxidising stock are stored apart. A reaction could release toxic vapours.
  • CorrosiveCorrosive stock can react with oxidisers, releasing heat or fumes.

Named chemicals to keep apart

  • Acetic acidMany oxidisers release toxic gas or become unstable in contact with acid.
  • AcetoneOxidisers can ignite flammable materials or make a fire far more intense.
  • Ammonia solutionSome oxidisers react strongly with alkalis, and ammonia based stock is especially at risk.
  • EthanolOxidisers can ignite flammable materials or make a fire far more intense.
  • FormalinToxic and oxidising stock are stored apart. A reaction could release toxic vapours.
  • HexaneOxidisers can ignite flammable materials or make a fire far more intense.
  • Hydrochloric acidMany oxidisers release toxic gas or become unstable in contact with acid.
  • Mercury(II) chlorideToxic and oxidising stock are stored apart. A reaction could release toxic vapours.
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  • MethanolOxidisers can ignite flammable materials or make a fire far more intense.
  • Nitric acidMany oxidisers release toxic gas or become unstable in contact with acid.
  • Potassium hydroxideSome oxidisers react strongly with alkalis, and ammonia based stock is especially at risk.
  • Sodium cyanideToxic and oxidising stock are stored apart. A reaction could release toxic vapours.
  • Sodium hydroxideSome oxidisers react strongly with alkalis, and ammonia based stock is especially at risk.
  • Sulfuric acidMany oxidisers release toxic gas or become unstable in contact with acid.
  • Thionyl chlorideCorrosive stock can react with oxidisers, releasing heat or fumes.
  • TolueneOxidisers can ignite flammable materials or make a fire far more intense.
  • Zinc chlorideCorrosive stock can react with oxidisers, releasing heat or fumes.

Common quantities we collect

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.

Where it is commonly held

Hazard statements

  • H272 May intensify fire; oxidiser.
  • H302 Harmful if swallowed.
  • H317 May cause an allergic skin reaction.
  • H318 Causes serious eye damage.
  • H334 May cause allergy or asthma symptoms or breathing difficulties if inhaled.
  • H341 Suspected of causing genetic defects.
  • H350i May cause cancer by inhalation.
  • H360F May damage fertility.
  • H410 Very toxic to aquatic life with long lasting effects.
Precautionary statements
  • P203 Obtain, read and follow all safety instructions before use.
  • P233 Keep container tightly closed.
  • P260 Do not breathe dust, fume, gas, mist, vapours or spray.
  • P261 Avoid breathing dust, fume, gas, mist, vapours or spray.
  • P271 Use only outdoors or in a well-ventilated area.
  • P272 Contaminated work clothing should not be allowed out of the workplace.
  • 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.
  • P302+P352 IF ON SKIN: Wash with plenty of water.
  • P304+P340 IF INHALED: Remove person to fresh air and keep comfortable for breathing.
  • P318 If exposed or concerned, get medical advice.
  • P321 Specific treatment (see supplemental first aid instruction on this label).
  • P333+P317 If skin irritation or rash occurs: Get medical help.
  • P342+P316 If experiencing respiratory symptoms: Get emergency medical help immediately.
  • P362+P364 Take off contaminated clothing. And wash it before reuse.
  • P391 Collect spillage.
  • P403 Store in a well-ventilated place.
  • P405 Store locked up.
  • P501 Dispose of contents and container in accordance with local, regional, national and international regulations.
  • P210 Keep away from heat, hot surfaces, sparks, open flames and other ignition sources. No smoking.
  • P220 Keep away from clothing and other combustible materials.
  • P264 Wash hands and exposed skin thoroughly after handling.
  • P264+P265 Wash hands and exposed skin thoroughly after handling. Do not touch eyes.
  • P270 Do not eat, drink or smoke when using this product.
  • P301+P317 IF SWALLOWED: Get medical help.
  • P305+P354+P338 IF IN EYES: Immediately rinse with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
  • P317 Get medical help.
  • P330 Rinse mouth.
  • P370+P378 In case of fire: Use suitable extinguishing media to extinguish.

Substance as classified, dilutions may differ.

Questions

Why does cobalt nitrate need oxidiser storage?

It is classified as an oxidiser that may intensify fire. Keep it on non-combustible shelving away from organic material, solvents, acids, alkalis and ammonia based stock.

The crystals have gone wet. Is that serious?

It means the salt has drawn water from the air. It is still an oxidising, hazardous stock. Keep the lid on, stand it on a tray away from organics, and describe the dampness when you ask for collection.

What other warnings apply?

It is classified as a sensitiser, as able to cause cancer by inhalation, as suspected of causing genetic defects, as able to damage fertility and as very toxic to aquatic life. Keep it locked and recorded.

Which waste code do we use?

A laboratory pack uses 16 05 06*. Discarded inorganic chemical outside a laboratory pack uses 16 05 07*. Say that it is an oxidiser so the grouping is correct.

Guidance only. Check your own risk assessment and your supplier's safety data sheet.

Hazard data source: PubChem GHS Classification, retrieved 31 Oct 2026. Formula CoN2O6. EC number 233-402-1.

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