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

Sodium nitrate (CAS 7631-99-4): storage and disposal

School and college prep rooms often keep a tub of sodium nitrate for solubility and fertiliser experiments, usually tucked on a general salts shelf. It is classified as an oxidiser that may intensify fire, and as causing serious eye irritation. That fire hazard is the reason it cannot live with the organic and reducing chemicals nearby.

CAS number
7631-99-4
Form
Solid
Storage class
Oxidiser
Signal word
Danger
Usual EWC code
16 05 06*
  • Oxidising pictogramOxidising
  • Harmful or irritant pictogramHarmful or irritant

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

Prep rooms often keep nitrates beside other salts, and that is the habit to break. Sodium nitrate goes in a separate, labelled space on non-combustible shelving where possible, away from organic and reducing materials. Our list of poor neighbours includes peroxide forming ethers such as diethyl ether, diisopropyl ether, 1,4-dioxane and 1,2-dimethoxyethane, as well as activated charcoal, aluminium powder, glucose and hydrazine hydrate. Strong oxidisers can form mixtures with these that burn fiercely or explode. Acids, alkalis, corrosive stock and anything that can ignite are kept elsewhere. Paper labels and cardboard trays are better avoided under this tub.

How to tell it has deteriorated

Caking is the common change, as nitrate salts take up moisture and set into lumps. A damp patch on the shelf, staining or a corroded cap point to the same thing. The thing to check is contamination with paper, wood dust or organic residue, because an oxidiser contaminated this way becomes a fire risk and the jar should not be opened. A cracked tub, a faded label or a missing receipt date count as well. If the jar has stood next to organic material, record it and leave it closed.

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.

Specialist collection is the route for sodium nitrate, and never a bin, where it could feed a fire. Record the weight, whether the contents look caked or contaminated and the condition of the tub, and describe it as an oxidiser. The laboratory chemical code applies, with the inorganic discarded-chemical variant outside a lab pack. A school should not mix it with other waste to get rid of it. The carrier packs it separately from ethers, organic compounds, charcoal, aluminium powder and glucose, in an oxidiser group.

Waste codes and transport details for Sodium 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

  • 1,2-DimethoxyethanePeroxide forming ethers can ignite or explode with strong oxidisers.
  • 1,4-DioxanePeroxide forming ethers can ignite or explode with strong oxidisers.
  • 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.
  • Activated charcoalStrong oxidisers can form mixtures with these materials that burn fiercely or explode.
  • Aluminium powderStrong oxidisers can form mixtures with these materials that burn fiercely or explode.
  • Ammonia solutionSome oxidisers react strongly with alkalis, and ammonia based stock is especially at risk.
  • Diethyl etherPeroxide forming ethers can ignite or explode with strong oxidisers.
Show 14 more
  • Diisopropyl etherPeroxide forming ethers can ignite or explode with strong oxidisers.
  • 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.
  • GlucoseStrong oxidisers can form mixtures with these materials that burn fiercely or explode.
  • 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.
  • Magnesium ribbonStrong oxidisers can form mixtures with these materials that burn fiercely or explode.
  • Potassium cyanideCyanides react violently with strong oxidisers.
  • Red phosphorusStrong oxidisers can form mixtures with these materials that burn fiercely or explode.
  • Sodium cyanideCyanides react violently with strong oxidisers.
  • SucroseStrong oxidisers can form mixtures with these materials that burn fiercely or explode.
  • SulfurStrong oxidisers can form mixtures with these materials that burn fiercely or explode.
  • TetrahydrofuranPeroxide forming ethers can ignite or explode with strong oxidisers.
  • White phosphorusPhosphorus can ignite or explode with oxidisers.

Common quantities we collect

Usually held as: solid.

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.
  • H319 Causes serious eye irritation.
Precautionary statements
  • 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.
  • P280 Wear protective gloves, protective clothing, eye protection and face protection.
  • P301+P317 IF SWALLOWED: Get medical help.
  • P305+P351+P338 IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
  • P330 Rinse mouth.
  • P337+P317 If eye irritation persists: Get medical help.
  • P370+P378 In case of fire: Use suitable extinguishing media to extinguish.
  • P501 Dispose of contents and container in accordance with local, regional, national and international regulations.

Substance as classified, dilutions may differ.

Questions

Why can't sodium nitrate go in general waste?

It is classified as an oxidiser that may intensify fire. In a bin it can meet paper and other organic waste, so it is collected as hazardous waste by specialist carrier.

What should it be kept away from in a prep room?

Organic and reducing materials, ethers, charcoal, aluminium powder, glucose and hydrazine hydrate. Give it its own labelled space on non-combustible shelving, and keep paper and cardboard out from under the tub.

Our tub is caked. Is it dangerous?

Caking shows moisture has entered. The hazard stays as classified, so the main concern is contamination with organic matter. Keep it closed and request collection.

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 NNaO3. EC number 231-554-3.

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