Bottle of solution of sodium dodecyl sulfate for use in the laboratory. The critical micelle concentration (CMC) in pure water at 25 Â°C is 8.2 mM, and the aggregation number at this concentration is usually considered to be about 62. The micelle ionization fraction (Î±) is around 0.3 (or 30%).
Definition: A pure substance is a sample of matter with both definite and constant composition with distinct chemical properties.
Definition. 1  As a noun, the common definition of chemical is a substance that is produced or used in a process (reaction) involving changes to atoms or molecules. The term is sometimes defined more broadly as a substance. 2  As an adjective, chemical means of or pertaining to chemistry. Chemistry is the study of matter and its transformations.