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

Sodium hydride (CAS 7646-69-7): storage and disposal

Held as a grey powder dispersed in oil, sodium hydride belongs mainly to university organic chemistry labs. It ignites in moist air, reacts violently with water and releases flammable gases that may ignite on their own. The mineral oil reduces exposure of the hydride to air and moisture, but the condition of the sealed container and any protective inert atmosphere are also important. Residue on the thread may indicate a compromised container. Holdings are not quoted online and go through a manual enquiry.

CAS number
7646-69-7
Form
Solid
Storage class
Flammable
Signal word
Danger
Usual EWC code
16 05 06*
  • Flammable pictogramFlammable

This chemical is a manual enquiry

This can become unstable or explosive, especially if it is old or has dried out. Nobody should move it until someone competent has looked at it, so we start with a conversation and usually a store assessment.

Reacts violently with water, ignites in moist air.

It cannot be priced through a form. Please do not open or move it. Call us or send an enquiry and we will talk through the safe next step, which is often a store assessment.

What to do this week

  1. Leave it where it is. If it looks old, crystalline or damaged, do not open or move it and keep people away from the shelf.
  2. Write down the label wording, the rough age and where it is stored, from a safe distance.
  3. Send us those details, and a photo if you can take one without touching it.

Safe storage in a school or lab

Anything water based has to stay clear: ammonia solution, formalin, hydrochloric acid, hydrogen peroxide, sodium hydroxide and sodium hypochlorite solution all count, because it releases heat and flammable gas on contact. Research groups tend to get this wrong in small ways. A bottle brought out of a cold store collects condensation at the thread, which is the worst place for it, and a part used bottle closed with tape instead of its proper seal lets moist air creep in. Where a supplier packed it under inert gas, the seal is part of the protection. Storage requires a dry, securely sealed container with the protective atmosphere specified by the supplier, segregated from water, acids and oxidisers. A fire-resistant cabinet alone does not provide protection against moisture. If a bottle looks poorly sealed, leave it and ask for advice.

How to tell it has deteriorated

Greasy residue on the cap, or an oil stained label, is the first clue that a bottle has been used more than once. Look next at the thread. A white crust may contain sodium hydroxide or other reaction products formed by exposure to moisture or air. Active sodium hydride may remain immediately beneath or beside it. Swelling suggests hydrogen has built up inside. Oil-dispersed sodium hydride is typically a grey solid distributed through protective mineral oil. Exposed dry powder should not be assumed safe or adequately protected from moisture. Dry powder left above the oil level has lost its protection and is the part most likely to ignite in moist air. Beyond these it gives few visual signs. Do not wipe the thread or open the bottle to check, and leave a swollen one where it stands.

How it must be disposed of

This does not go through our standard collection route. It is arranged by manual enquiry, and never goes down the drain or into general waste.

Record the supplier label, the date of receipt, whether the bottle is sealed or part used, and how it is closed, including any tape or film. Note any white crust at the thread, as that decides whether it can be touched at all. This stock is not quoted online, and the online quote path does not accept it. Send a manual enquiry, and a store assessment is recommended, because a competent chemist has to see it in person. Warning signs may call for an explosives or emergency specialist. Do not open it, move it or try to make it safe in the meantime, and keep it away from any sink, drain, bin or skip. Code 16 05 06* normally fits a university lab.

Waste codes and transport details for Sodium hydride
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: dispersion in oil.

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

  • H260 In contact with water releases flammable gases which may ignite spontaneously.

Substance as classified, dilutions may differ.

Questions

There is a white crust on the thread. Is the hydride under it still active?

Assume it is. The crust shows where moist air has reached the outer layer, and active material can remain just beneath it and inside the bottle. Turning the cap could disturb both. Leave it closed and describe the crust in your enquiry.

We handle reaction residues at the bench all the time. Can old bottles be dealt with the same way?

No. A small planned residue in a controlled reaction is a different job from an old bottle of unknown condition. The quantity is larger, the state of the contents is unknown, and nobody can see what is on the thread. Send a manual enquiry and leave the bottle alone.

Why can it not simply go on an online quote with our other solvent waste?

Because it reacts violently with water and ignites in moist air, so its condition has to be seen by a competent chemist before anyone can say how it leaves. It also cannot be grouped with ordinary waste solvents, some of which may hold traces of water.

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

Hazard data source: GB mandatory classification list (HSE), retrieved 31 Oct 2026. Formula HNa.

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