The critical micelle concentration CMC is the concentration of surfactants above which micelles start to form. In the case of sodium dodecyl sulfate SDS , it is an anionic surfactant commonly used in various applications, including detergents and laboratory experiments. The CMC of SDS in water at 25C is approximately 8.2 mM millimolar .To determine the CMC of a surfactant, one can use various techniques, such as surface tension measurements, conductivity measurements, or fluorescence spectroscopy. The CMC is typically obtained from the plot of a property e.g., surface tension, conductivity, or fluorescence intensity against the surfactant concentration. The point at which the plot shows a significant change in slope indicates the CMC.The significance of the CMC in micelle formation lies in its role as a threshold concentration for micelle formation. Below the CMC, surfactant molecules exist primarily as monomers, adsorbing at interfaces e.g., air-water interface and reducing surface tension. Above the CMC, the surfactant molecules aggregate to form micelles, which are spherical structures with hydrophobic tails pointing inward and hydrophilic heads pointing outward. This arrangement minimizes the contact between the hydrophobic tails and water, thus reducing the system's free energy.Micelles play a crucial role in various applications, such as solubilizing hydrophobic compounds in water, stabilizing emulsions, and enhancing the cleaning efficiency of detergents. In the context of laboratory experiments, SDS is often used in electrophoresis techniques to denature proteins and provide them with a uniform negative charge, allowing for separation based on size.