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.
Substance. Definition. noun, plural:substances. (1) The physical matter, material or that of which an organ or body consists. (2) (chemistry) A material, matter or that which has definite chemical composition and distinct properties.(3) The most vital or essential part of something. (4) Drugs, as in substance abuse.oun, plural:substances. (1) The physical matter, material or that of which an organ or body consists. (2) (chemistry) A material, matter or that which has definite chemical composition and distinct properties. (3) The most vital or essential part of something. (4) Drugs, as in substance abuse.