What does CAS number mean? –Understanding the “identity card” of a chemical substance
What does a CAS number mean? In the chemical industry, a CAS Number is an important chemical identifier that uniquely identifies each chemical substance, and is assigned by the Chemical Abstracts Service (CAS) and is as important as a person’s ID card. By understanding the definition, structure and purpose of a CAS number, we can better understand its critical role in chemical research, production and trade.
What is CAS Number?
A CAS number, known as a Chemical Abstracts Service Registry Number, is a unique identifier consisting of a number and a dash that identifies each known chemical substance. a CAS number usually consists of a three-part number in the format “XXX-XX-X “. For example, the CAS number for water is 7732-18-5. the first part is usually an integer of up to 7 digits, the second part is a 2-digit number, and the third part is a 1-digit check digit. This structure makes each CAS number unique, ensuring accuracy and consistency in the identification of chemical substances in the global chemical industry.
What is the purpose of a CAS number?
After understanding what a CAS number means, we also need to know its main uses. In the chemical and chemical industry, CAS numbers are widely used in the following ways:
Substance identification and information retrieval: Since the names of chemical substances may vary from language to language or region to region, the CAS number, as a unique identifier, effectively avoids the confusion caused by these inconsistencies. Scientists, researchers and enterprises use CAS numbers to quickly and accurately retrieve detailed information about a chemical substance, including molecular structure, physicochemical properties, application areas and so on.

Regulatory compliance and safety management: Globally, CAS numbers are required by chemical management regulations in many countries and regions. For example, CAS number is necessary information in chemical safety data sheets (SDS). It helps companies and regulators to better manage the storage, transport and use of chemicals to ensure compliance with relevant regulations and safety standards.

International Trade and Supply Chain Management: In the international trade and transport of chemical products, CAS number serves as a common language, eliminating ambiguities and errors arising from differences in the names of chemical substances and promoting transparency and efficiency in the supply chain.

How to find and use CAS numbers?
After understanding what a CAS number means and its importance, we also need to know how to find and use a CAS number. There are several ways to obtain a CAS number:
Chemical literature and databases: CAS numbers originally came from the Chemical Abstracts Service database. Today, many online databases, such as PubChem, ChemSpider, and SciFinder, provide access to CAS numbers and their associated chemical substance information.

Chemical suppliers and manufacturers: Most chemical suppliers indicate CAS numbers in their product descriptions and labels to help customers identify and purchase the correct chemical substance.

The key to using CAS numbers is that they are unique and widely recognised. Whether a researcher is searching the chemical literature or a company is ensuring that its products comply with international standards, the CAS number is a convenient and reliable tool.
Why are CAS numbers so important?
A CAS number is more than just a number, it represents the common language of the chemical world. Knowing what a CAS number means helps to understand its central role in chemical identification, regulatory compliance, safety management and international trade. In today’s globalised world, the CAS number serves as an ‘identity card’ for chemicals, ensuring uniformity and transparency in the management of chemical substances across countries and regions.
Conclusion
What is the meaning of CAS number is not only a question of chemical specialisation, but also a point of knowledge with wide influence. Whether in research, production, or trade, the use of CAS numbers helps to reduce misunderstanding, improve efficiency, and ensure safety. Therefore, familiarising yourself with the concepts and uses of CAS numbers is essential for those working in chemistry or related industries.