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.
A drug is any substance that alters the central nervous system, brain chemistry or bodily functions. There is no single definition since there are different meanings of the word drug, with regard to medicine, government and street usage. Dictionary.com defines a drug as a chemical substance used in the treatment, cure, prevention, or diagnosis of disease or used to otherwise enhance physical or mental well-being.. Medicinal drugs may be prescribed by a doctor for a limited time frame or for use on a regular basis for chronic condition.