NIST Chemistry WebBook

Choose a search option for the substance you are studying, then inspect the specific data collection relevant to your question. The homepage credits different compilers for different kinds of measurements, so preserve that context when taking notes. Its documentation and special collections help distinguish one type of chemical data from another.

The guide explains name, formula and CAS-number searches. Select both the units and the data types you need before comparing results; these choices affect what is displayed and, for several search types, which species match.