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.
1 A pure substance is a form of matter that has a uniform composition and properties that are constant throughout the sample. 2  Mixtures are physical combinations of two or more elements and/or compounds. 3  Elements and compounds are both example of pure substances.ecall that a solution is a mixture of substances in such a way that the final product has the same composition throughout. Remember the example of vinegar that is 5%, by mass, acetic acid in water. This clear liquid is a solution since light easily passes through it and it never separates.