CAS Number

Last updated: March 19, 2024

What Does CAS Number Mean?

A CAS Number is unique numerical identifier for a chemical product. These numerical designations are maintained by the Chemical Abstracts Service (CAS) of the American Chemical Society.

CAS numbers are used across a range of databases, ensuring that the number is standardized across all of them and making it easier to retrieve pertinent information about chemical products.

Safeopedia Explains CAS Number

CAS numbers are up to 10 digits long and separated into three hyphenated parts. Ibuprofen, for instance, has an eight-digit, hyphenated CAS number: 15687-27-1.

These numbers are assigned sequentially as chemical products are added to the database and do not reflect any of the chemical’s properties. They are simply a means of identifying them.

While CAS numbers are primarily for chemical identification, the database also includes compounds such as alloys, isotopes, and polymers.

CAS Registry Information

Each CAS number is linked to an entry in the CAS Registry.

These entries contain key information about chemical products and compounds, such as:

  • Its molecular structure
  • Mass
  • Boiling point
  • Melting point
  • Density

It also lists other common names and identifiers for the substance.

CAS Registry entry for ibuprofen, listing its chemical number and various properties.

Source: CAS

CAS Numbers and Safety

While the CAS Registry contains information that is useful for scientific purposes, it does not provide information for the safe handling of chemical products

For that information, consult the product’s Safety Data Sheet (SDS). The SDS will include the substance’s CAS number along with everything you need to know to use it safely.

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