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

Copper(I) chloride (CAS 7758-89-6): storage and disposal

Copper(I) chloride is a pale solid held in school, college and university stores. It is classified as harmful if swallowed and as very toxic to aquatic life with long lasting effects, and is treated as hazardous waste. Unlike the blue and green copper(II) salts around it on the shelf, it changes colour as air reaches it, so a jar that is supposed to be pale often arrives at collection looking green.

CAS number
7758-89-6
Form
Solid
Storage class
General
Signal word
Warning
Usual EWC code, laboratory stock
16 05 06*
  • Harmful or irritant pictogramHarmful or irritant
  • Hazardous to the environment pictogramHazardous to the environment

What to do this week

  1. Without moving anything that looks damaged, check the label is readable and write down the opened date if it is not already there.
  2. Check it is stored as general stock, and apart from anything listed under "Do not store with" on this page. If nothing is listed, that does not prove it is safe with everything.
  3. If you no longer need it, add it to your disposal list so it can be included in a collection.

Safe storage in a school or lab

The enemy is air. Copper(I) chloride in a jar with a loose cap slowly changes as oxygen and damp reach it, so keep the cap tight, the jar dated on arrival and the neck clean. It is general class stock, so a dry, labelled, well organised store suits it, away from food grade supplies. Do not shelve it among the copper(II) chloride or sulfate jars, where the label is the only thing separating a pale salt from blue-green ones. Part-used jars from practicals should return to the store closed, and the cap thread should be wiped before it is screwed down.

How to tell it has deteriorated

Pale or off-white stock is as expected, and a green or blue-green tinge, starting at the surface and the neck of the jar, shows that air and damp have turned some of it into copper(II) material. Green crust on the cap thread is the clearest sign. Clumping points to moisture, and a faded label and an unknown date of receipt are as common here as elsewhere. A jar that has gone green is described as altered, and it should not be mixed back with fresh stock or topped up from another jar.

How it is disposed of

We arrange this by specialist collection. We do not publish a drain or general waste route for any chemical. It is normally packed in a general laboratory pack with compatible chemicals.

A green jar is partly something else, so start by telling the collection team the colour and how much of the contents has changed. List it apart from any copper(II) chloride, even if the two now look alike, because their descriptions differ. Very toxic effects on aquatic life rule out a sink, a drain, a general bin or a skip, and no one should try to treat a discoloured jar to restore it. The usual lab pack entry is 16 05 06*, and 16 05 07* normally applies if it goes as a discarded inorganic chemical on its own, though the producer classifies the waste. The cap stays tight and the jar upright until it is lifted.

Waste codes for Copper(I) chloride
Usual EWC code, laboratory stock16 05 06*
Discarded inorganic chemical, not a laboratory pack16 05 07*
Usually classed as hazardous wasteYes

The code depends on where the waste came from and what it contains, and classifying it is the producer's duty. Use the waste code finder to see why.

Common quantities

Usually held as: solid.

Tell us the container size and how many you hold. An estimate is enough to start with, and some items cannot be priced until someone has looked at them.

Where it is commonly held

Hazard statements

  • H302 Harmful if swallowed.
  • H410 Very toxic to aquatic life with long lasting effects.
Precautionary statements
  • P264 Wash hands and exposed skin thoroughly after handling.
  • P270 Do not eat, drink or smoke when using this product.
  • P273 Avoid release to the environment.
  • P301+P317 IF SWALLOWED: Get medical help.
  • P330 Rinse mouth.
  • P391 Collect spillage.
  • 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 copper(I) chloride turned green?

Air and damp change it into copper(II) material, which is blue-green. The change usually starts at the surface and the neck of the jar. It is still collected as hazardous waste, so describe the colour and keep the cap tight.

Can we mix the green crust back into the jar?

No. Mixing altered material into stock leaves contents you cannot describe. Keep the jar closed, label it as partly changed and put it forward for collection with the colour noted.

Is it hazardous waste?

Yes. It is classified as harmful if swallowed and very toxic to aquatic life with long lasting effects, so it is treated as hazardous waste and must not go to drain or general waste.

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 ClCu.

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