Propanoic acid (CAS 79-09-4): storage and disposal
Propanoic acid is held neat as a liquid in school and college prep rooms and university labs. It causes severe skin burns and eye damage. It has a sharp, unpleasant smell that gives away a failing cap before anything else does. What it stands beside, and whether the room smells of it, tell a holder more than the colour of the liquid.
- CAS number
- 79-09-4
- Form
- Liquid
- Storage class
- Acid
- Signal word
- Danger
- Usual EWC code
- 16 05 06*
Corrosive
What to do this week
- Check the label is readable and write down the opened date if it is not already there.
- Check it is stored as acid stock and apart from the items listed under "Do not store with".
- 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
Neat propanoic acid is corrosive and flammable, so it must be kept away from alkalis, oxidisers, heat and ignition sources. Acids and alkalis react with strong heat and spattering if they meet, and many oxidisers release harmful gas or become unstable in contact with acid, so a mixed shelf is the usual cause of trouble. Keep the bottle low down on an acid-resistant tray, in a store suitable for both corrosive and flammable liquids, with the cap fully seated and clean. Because it causes severe burns, it should never sit at head height. Poisonous stock needs its own cabinet apart from it, and the tray should be deep enough to hold the bottle if it cracks.
How to tell it has deteriorated
Start with the bottle and its label. Propanoic acid has a sharp, rancid smell, so a smell at the shelf or in the store room means the cap is not sealing. Beyond that, look for a perished or brittle cap, crust around the neck, corrosion on nearby fittings and a cracked container. Fumes on opening and a stained or faded label are also general signs. The liquid itself gives few visual changes with age, so the evidence is the container and the room. A bottle that smells through a closed cap or has a damaged neck should stay upright on its tray until it is collected.
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 corrosive acid laboratory pack with compatible chemicals.
A sink or drain, a bin and a skip are all closed off to it, and it must not be diluted or neutralised first. It leaves only through a specialist collection. As a discarded organic chemical outside a lab pack, it takes the code 16 05 08*. Note the volume left, whether the bottle is the original, the state of the cap and whether the store smells of it. A bottle that has leaked or has a crusted neck is awkward to lift, so say so when booking. The collector packs it with other organic acids and apart from alkalis and oxidisers.
| EWC code, laboratory chemicals | 16 05 06* |
|---|---|
| Discarded organic chemical, not a laboratory pack | 16 05 08* |
| Hazardous waste | Yes |
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
- FlammableOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
- AlkaliAcids and alkalis react with strong heat and spattering if they meet.
- OxidiserMany oxidisers release toxic gas or become unstable in contact with acid.
- ToxicToxic stock is stored apart from acids. Several toxic salts release toxic gas in contact with acid.
Named chemicals to keep apart
- AcetoneOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
- Ammonia solutionAcids and alkalis react with strong heat and spattering if they meet.
- Calcium hypochloriteMany oxidisers release toxic gas or become unstable in contact with acid.
- EthanolOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
- FormalinToxic stock is stored apart from acids. Several toxic salts release toxic gas in contact with acid.
- HexaneOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
- Hydrogen peroxideMany oxidisers release toxic gas or become unstable in contact with acid.
- Mercury(II) chlorideToxic stock is stored apart from acids. Several toxic salts release toxic gas in contact with acid.
Show 7 more
- MethanolOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
- Potassium hydroxideAcids and alkalis react with strong heat and spattering if they meet.
- Potassium nitrateMany oxidisers release toxic gas or become unstable in contact with acid.
- Potassium permanganateMany oxidisers release toxic gas or become unstable in contact with acid.
- Sodium cyanideToxic stock is stored apart from acids. Several toxic salts release toxic gas in contact with acid.
- Sodium hydroxideAcids and alkalis react with strong heat and spattering if they meet.
- TolueneOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
Common quantities we collect
Usually held as: neat.
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
- H314 Causes severe skin burns and eye damage.
Precautionary statements
- P260 Do not breathe dust, fume, gas, mist, vapours or spray.
- P264 Wash hands and exposed skin thoroughly after handling.
- P280 Wear protective gloves, protective clothing, eye protection and face protection.
- P301+P330+P331 IF SWALLOWED: Rinse mouth. Do NOT induce vomiting.
- P302+P361+P354 IF ON SKIN: Take off immediately all contaminated clothing. Immediately rinse with water for several minutes.
- P304+P340 IF INHALED: Remove person to fresh air and keep comfortable for breathing.
- P305+P354+P338 IF IN EYES: Immediately rinse with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
- P316 Get emergency medical help immediately.
- P321 Specific treatment (see supplemental first aid instruction on this label).
- P363 Wash contaminated clothing before reuse.
- P405 Store locked up.
- P501 Dispose of contents and container in accordance with local, regional, national and international regulations.
Substance as classified, dilutions may differ.
Questions
Why does our chemical store smell sharp and sour?
Propanoic acid has a sharp, rancid smell, and a store that smells of it usually has a bottle with a poor cap seal or a leak. Check the caps and necks of acid bottles, keep ventilation running and list damaged bottles for collection.
Can propanoic acid share a shelf with the alkalis?
No. Acids and alkalis react with strong heat and spattering if they meet. Keep it low down on an acid-resistant tray, in the corrosive store, with alkalis on a separate shelf or space.
What do we do with a bottle that has a crusted neck?
Leave the cap on, keep the bottle upright on its tray and do not try to force or clean the neck. Record the crust, the strength and the volume, and list it for collection.
