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

Sodium chlorate (CAS 7775-09-9): storage and disposal

A strong oxidiser classified for fire or explosion, toxicity if swallowed and long lasting harm to aquatic life, sodium chlorate turns up in school, college and university chemical stores, usually as a solid in a glass or plastic jar. What it is stored near decides the risk, since organic material, powdered metals and ammonium salts all change the picture. It goes by specialist collection only.

CAS number
7775-09-9
Form
Solid
Storage class
Oxidiser
Signal word
Danger
Usual EWC code
16 05 06*
  • Oxidising pictogramOxidising
  • Acute toxicity pictogramAcute toxicity
  • 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

Fire and explosion risk decides where this solid goes: a separate, labelled space on non-combustible shelving, well clear of flammable, organic and reducing materials. Activated charcoal and aluminium powder are stock items that should never share its shelf. Ammonium salts such as ammonium nitrate and ammonium chloride must be kept away as well, because chlorates and ammonium salts can form unstable ammonium chlorate. Peroxide forming ethers like dioxane are another bad neighbour. Acids, alkalis, toxic stock and corrosives also stay elsewhere. The solid absorbs moisture, so the cap needs to be tight, and a school prep room does better with a metal or plastic tray than bare wooden shelving, where spilt grains soak into the wood.

How to tell it has deteriorated

Start with the jar itself: a faded label, a cracked or stained cap, or crystals around the neck show that the seal has failed. This solid absorbs moisture, so damp patches, caking and a lumpy base are common on older stock. Spilt grains on paper labels, cardboard boxes, wooden shelves or cloth are the bigger worry, because anything organic soaked in it becomes very flammable once it dries. Rust on nearby metal fittings and dust or paper inside the container are further signs. Do not scrape, sweep or brush residue to tidy it. Report it and leave the jar where it is until it has been assessed.

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.

Oxidisers are packed in a lab pack group of their own, apart from flammable, acid and organic stock, because a box that mixes a strong oxidiser with fuel is the main way a collection goes wrong. Waste code 16 05 06* is the usual entry, and UN 1495 is the transport number. Hazardous waste paperwork applies, with a consignment note raised for the collection. It does not go into a sink, a drain, a general waste bin or a skip, and should not be treated first. Note the container size, whether any is spilt or damp, and what it sits beside, because grains spilt around the jar need describing too.

Waste codes and transport details for Sodium chlorate
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.
  • 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.
  • Ammonium acetateChlorates and ammonium salts can form unstable ammonium chlorate.
  • Ammonium carbonateChlorates and ammonium salts can form unstable ammonium chlorate.
  • Ammonium chlorideChlorates and ammonium salts can form unstable ammonium chlorate.
  • Ammonium nitrateChlorates and ammonium salts can form unstable ammonium chlorate.
Show 15 more
  • Ammonium oxalateChlorates and ammonium salts can form unstable ammonium chlorate.
  • Ammonium sulfateChlorates and ammonium salts can form unstable ammonium chlorate.
  • Ammonium thiocyanateChlorates and ammonium salts can form unstable ammonium chlorate.
  • Diethyl etherPeroxide forming ethers can ignite or explode with strong oxidisers.
  • Diisopropyl etherPeroxide forming ethers can ignite or explode with strong oxidisers.
  • GlucoseStrong oxidisers can form mixtures with these materials that burn fiercely or explode.
  • Hydrobromic acidChlorates and strong acids can form explosive chlorine dioxide.
  • Hydrochloric acidChlorates and strong acids can form explosive chlorine dioxide.
  • Hydroiodic acidChlorates and strong acids can form explosive chlorine dioxide.
  • Magnesium ribbonStrong oxidisers can form mixtures with these materials that burn fiercely or explode.
  • Nitric acidChlorates and strong acids can form explosive chlorine dioxide.
  • Perchloric acidChlorates and strong acids can form explosive chlorine dioxide.
  • Phosphoric acidChlorates and strong acids can form explosive chlorine dioxide.
  • Potassium cyanideCyanides react violently with strong oxidisers.
  • Red phosphorusStrong oxidisers can form mixtures with these materials that burn fiercely or explode.

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

  • H271 May cause fire or explosion; strong oxidiser.
  • H301 Toxic if swallowed.
  • H411 Toxic to aquatic life with long lasting effects.
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.
  • P270 Do not eat, drink or smoke when using this product.
  • P280 Wear protective gloves, protective clothing, eye protection and face protection.
  • P283 Wear fire resistant or flame retardant clothing.
  • P301+P316 IF SWALLOWED: Get emergency medical help immediately.
  • P306+P360 IF ON CLOTHING: Rinse immediately contaminated clothing and skin with plenty of water before removing clothes.
  • P321 Specific treatment (see supplemental first aid instruction on this label).
  • P330 Rinse mouth.
  • P370+P378 In case of fire: Use suitable extinguishing media to extinguish.
  • P371+P380+P375 In case of major fire and large quantities: Evacuate area. Fight fire remotely due to the risk of explosion.
  • P405 Store locked up.
  • P420 Store separately.
  • P501 Dispose of contents and container in accordance with local, regional, national and international regulations.
  • P273 Avoid release to the environment.
  • P301+P317 IF SWALLOWED: Get medical help.
  • P391 Collect spillage.

Substance as classified, dilutions may differ.

Questions

Why is sodium chlorate kept away from ammonium salts?

Chlorates and ammonium salts can form unstable ammonium chlorate. Ammonium nitrate, chloride, carbonate and acetate all count, so keep any ammonium compound on a different shelf, ideally in a different cupboard, from the chlorate jar.

What happens if it spills onto paper or wood?

Clothing or organic material soaked in sodium chlorate becomes very flammable once dry. Do not sweep or brush up the residue. Keep ignition sources away, report the spill and leave the jar where it is until it has been assessed.

How should an old tub from a school store be handled?

Check the label, cap and shelf for damp, caking, stains or organic dust. If the jar is undated or shows any of these, leave it undisturbed and request specialist assessment, describing exactly what can be seen without handling it.

Can it go with other waste chemicals in one box?

It is packed in a lab pack with compatible oxidisers only, never with flammable, acid, organic or toxic stock. Keep it out of mixed boxes you assemble yourself and let the collection team decide the grouping.

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 ClNaO3. EC number 231-887-4.

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