Ammonium thiocyanate (CAS 1762-95-4): storage and disposal
Ammonium thiocyanate turns up in school, college and university stores as colourless crystals used for iron(III) tests. It is classified as harmful by swallowing, skin contact and inhalation, as causing serious eye damage and as harmful to aquatic life with long lasting effects. The crystals take up water so readily that an old jar is often a pool of liquid with crystals in it.
- CAS number
- 1762-95-4
- Form
- Solid
- Storage class
- General
- Signal word
- Danger
- Usual EWC code
- 16 05 06*
Corrosive
Harmful or irritant
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 general 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
On the shelf, the question is what sits next to it. As an ammonium salt, ammonium thiocyanate must be kept away from strong alkalis, because sodium hydroxide and potassium hydroxide release ammonia gas from ammonium salts. Chlorates, including potassium chlorate and sodium chlorate, can form unstable ammonium chlorate, and sodium nitrite can react violently with ammonium salts on heating. School stores often keep these on one inorganic salts shelf, which needs splitting. The jar should sit in a dry, labelled store, dated on arrival, and the cap kept tight. Because it can cause serious eye damage, keep it below eye level.
How to tell it has deteriorated
Damp is the plain sign. Ammonium thiocyanate crystals draw water from the air, so an old tub tends to show wet crystals, a sticky mass or a pool of liquid at the base. The cap may be crusted or stuck, and the label often streaked with liquid that has crept up the jar. These changes mean the contents are no longer reliable. A jar that has been topped up or whose label no longer reads clearly should be treated as unknown stock. Do not open a wet jar to examine it, given the eye damage classification.
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 non-regulated or low hazard laboratory pack with compatible chemicals.
How it is grouped depends on the form: dry crystals go in a lab pack with compatible inorganic solids, while a wet jar is described as a liquid and kept upright. Record the quantity, the cap condition and the label wording. The laboratory chemical code applies, with the inorganic discarded-chemical variant outside a lab pack. Because it is harmful to aquatic life it must not go down a sink or drain, and it should not be mixed with alkali or acid. The carrier keeps it apart from alkalis, chlorates and nitrites.
| EWC code, laboratory chemicals | 16 05 06* |
|---|---|
| Discarded inorganic chemical, not a laboratory pack | 16 05 07* |
| 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
Named chemicals to keep apart
- Potassium chlorateChlorates and ammonium salts can form unstable ammonium chlorate.
- Potassium hydroxideStrong alkalis release ammonia gas from ammonium salts.
- Sodium chlorateChlorates and ammonium salts can form unstable ammonium chlorate.
- Sodium hydroxideStrong alkalis release ammonia gas from ammonium salts.
- Sodium nitriteNitrites and ammonium salts can react violently on heating.
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
- H302 Harmful if swallowed.
- H312 Harmful in contact with skin.
- H318 Causes serious eye damage.
- H332 Harmful if inhaled.
- H412 Harmful to aquatic life with long lasting effects.
Precautionary statements
- P261 Avoid breathing dust, fume, gas, mist, vapours or spray.
- 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.
- P271 Use only outdoors or in a well-ventilated area.
- P273 Avoid release to the environment.
- P280 Wear protective gloves, protective clothing, eye protection and face protection.
- P301+P317 IF SWALLOWED: Get medical help.
- P302+P352 IF ON SKIN: Wash with plenty of water.
- 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.
- P317 Get medical help.
- P321 Specific treatment (see supplemental first aid instruction on this label).
- P330 Rinse mouth.
- P362+P364 Take off contaminated clothing. And wash it before reuse.
- P501 Dispose of contents and container in accordance with local, regional, national and international regulations.
Substance as classified, dilutions may differ.
Questions
Why has our ammonium thiocyanate turned to liquid?
The crystals pull water from the air until they dissolve in it. It means the cap has not sealed well. The classified hazards stay as they are, so keep the jar closed and upright and arrange collection.
Why keep it away from sodium hydroxide?
Strong alkalis release ammonia gas from ammonium salts. Keep them in separate cabinets, never on one tray, and never combine leftovers to use them up.
Is it acceptable to wash small amounts away?
No. It is harmful to aquatic life with long lasting effects and must never go down a sink or drain, even in small amounts. It is collected by specialist carrier as hazardous waste.
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