The critical micelle concentration CMC of sodium dodecyl sulfate SDS in water at 25C is approximately 8.2 x 10^-3 mol/L or 8.2 mM. This value can vary slightly depending on the source, but it is generally accepted to be around this concentration.Micelle formation is a process in which amphiphilic molecules, like SDS, spontaneously aggregate in an aqueous solution to minimize the contact between their hydrophobic parts and water. SDS has a polar sulfate head group hydrophilic and a long hydrocarbon tail hydrophobic . When the concentration of SDS in water reaches the CMC, the amphiphilic molecules begin to aggregate into spherical structures called micelles.In a micelle, the hydrophobic tails are sequestered in the interior, while the hydrophilic head groups face the surrounding water. This arrangement minimizes the contact between the hydrophobic tails and water, thus reducing the overall free energy of the system. Micelles can solubilize hydrophobic molecules in their core, which is one of the reasons they are used in various applications, such as detergents and drug delivery systems.The CMC is an important parameter because it indicates the concentration at which micelles begin to form. Below the CMC, the amphiphilic molecules exist primarily as monomers in the solution. Above the CMC, micelles are formed, and the concentration of monomers remains relatively constant.