Currently, the mhchem bundle consists of two packages: mhchem
and rsphrase. The mhchem package provides two commands: one for
typesetting chemical molecular formulae and one for typesetting
chemical equations with these formulae. The rsphrase package
contains the text of all official Risk and Safety (R and S)
Phrases that are used to label chemicals. At the time being,
these phrases are available in Danish, English, French, German
(current spelling), and Spanish.