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

Calcium metal (CAS 7440-70-2): storage and disposal

Calcium granules are held in school, college and university stores for reactions with water, and for the gas collection demonstration. The classified hazard is that contact with water releases flammable gas. That single hazard drives every decision about the jar, from the shelf to the way the lid is checked, because the surrounding stock is mostly water based.

CAS number
7440-70-2
Form
Solid
Storage class
Flammable
Signal word
Danger
Usual EWC code
16 05 06*
  • Flammable pictogramFlammable

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 flammable 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

A dry shelf is more important than any other detail. Calcium granules react with water and release hydrogen, so keep the jar away from ammonia solution, formalin, hydrochloric acid, hydrogen peroxide, sodium hydroxide and sodium hypochlorite, and from anything else with water in it. Schools often store this metal beside the aqueous reagent shelf, and that needs to change. The cap should seal tightly, ideally with the jar placed in a second dry container. Oxidisers and corrosive stock are kept elsewhere too, as they can feed a fire. Date the jar on arrival and check the lid at each stock take.

How to tell it has deteriorated

Old granules form a white surface layer as they take up moisture, so a dull, chalky coating on the metal is the thing to look for. Under the layer the metal has been reacting slowly with damp air. Look also at the cap and thread, since corrosion or a swollen lid shows moisture and gas have been present. Loose white powder at the bottom of the jar, damp patches or a smell of dampness all mean the seal has failed. Do not open the jar to inspect the granules, and do not attempt to scrape the layer away.

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 flammable laboratory pack with compatible chemicals.

The way calcium leaves the site is by specialist collection of the whole jar, unopened. Record the jar size, how much metal is left and what the lid looks like. It must not be added to water, a sink or a drain to use it up, and no one should try to burn it off or react it away. The inorganic chemical variant of the code applies outside a lab pack. The carrier packs it dry, upright and apart from any water based stock, with the paperwork for a hazardous movement.

Waste codes and transport details for Calcium metal
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

  • OxidiserOxidisers can ignite flammable materials or make a fire far more intense.
  • AcidOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
  • CorrosiveA leak of corrosive stock can break down flammable containers and feed a fire.

Named chemicals to keep apart

  • Acetic acidOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
  • Ammonia solutionReacts with water, releasing heat and often a flammable or corrosive gas, so keep it away from all water based stock.
  • Calcium hypochloriteOxidisers can ignite flammable materials or make a fire far more intense.
  • FormalinReacts with water, releasing heat and often a flammable or corrosive gas, so keep it away from all water based stock.
  • Hydrochloric acidReacts with water, releasing heat and often a flammable or corrosive gas, so keep it away from all water based stock.
  • Hydrogen peroxideReacts with water, releasing heat and often a flammable or corrosive gas, so keep it away from all water based stock.
  • Nitric acidOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
  • Potassium nitrateOxidisers can ignite flammable materials or make a fire far more intense.
Show 6 more
  • Potassium permanganateOxidisers can ignite flammable materials or make a fire far more intense.
  • Sodium hydroxideReacts with water, releasing heat and often a flammable or corrosive gas, so keep it away from all water based stock.
  • Sodium hypochloriteReacts with water, releasing heat and often a flammable or corrosive gas, so keep it away from all water based stock.
  • Sulfuric acidOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
  • Thionyl chlorideA leak of corrosive stock can break down flammable containers and feed a fire.
  • Zinc chlorideA leak of corrosive stock can break down flammable containers and feed a fire.

Common quantities we collect

Usually held as: granules.

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

  • H261 In contact with water releases flammable gases.
Precautionary statements
  • P231+P232 Handle and store contents under inert gas. Protect from moisture.
  • P280 Wear protective gloves, protective clothing, eye protection and face protection.
  • P370+P378 In case of fire: Use suitable extinguishing media to extinguish.
  • P402+P404 Store in a dry place. Store in a closed container.
  • P501 Dispose of contents and container in accordance with local, regional, national and international regulations.

Substance as classified, dilutions may differ.

Questions

Why does the calcium in our jar look white and chalky?

Old granules form a white surface layer as moisture is taken up. It shows the seal has let damp in. Leave the jar closed and request collection rather than scraping or washing the metal.

Can calcium granules be used up by dropping them in water?

No. Contact with water releases flammable gas, and doing it to dispose of stock is not an approved route. Keep the jar closed and dry and ask for specialist collection.

What should be kept away from it on the shelf?

Anything water based, including ammonia solution, formalin, hydrochloric acid, hydrogen peroxide, sodium hydroxide and sodium hypochlorite. Keep oxidisers and corrosive bottles on a different shelf too, and check the lid each term.

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 Ca. EC number 231-179-5.

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