This is the 8988th most frequent French word.
chimique
"Relating to or involving chemistry."
Here, 'chimique' is used as an adjective describing 'substance', indicating its scientific or chemical nature.
La substance chimique réagissait dans le laboratoire.
The chemical substance reacted in the laboratory.
In this sentence, 'chimique' serves as an adjective modifying 'réactions', referring to processes resulting from chemistry.
Nous avons étudié les réactions chimiques en classe.
We studied chemical reactions in class.
Here, 'chimique' is again an adjective describing 'composés', implying the absence of chemical elements or materials.