The critical micelle concentration CMC of a surfactant, such as sodium dodecyl sulfate SDS , is the concentration at which the surfactant molecules start to aggregate and form micelles in a solution. The CMC is an important parameter for understanding the behavior of surfactants in various applications, such as detergents, emulsifiers, and stabilizers.The CMC of SDS is typically around 8 x 10^-3 mol/L or 8 mM at room temperature 25C in pure water. However, the CMC can be influenced by various factors, such as temperature, concentration of the solution, and the presence of other ions or additives.1. Temperature: The CMC of SDS generally decreases with increasing temperature. This is because the hydrophobic effect, which drives micelle formation, becomes more pronounced at higher temperatures. As a result, the surfactant molecules are more likely to aggregate and form micelles at elevated temperatures. The relationship between CMC and temperature can be described by the following empirical equation:CMC = CMC0 * 1 - k * T - T0 where CMC0 is the CMC at a reference temperature T0 usually 25C , k is a temperature coefficient, and T is the temperature of interest.2. Concentration of the solution: The CMC is an inherent property of the surfactant and does not directly depend on the concentration of the solution. However, the concentration of the solution can affect the CMC indirectly by changing the ionic strength or the presence of other ions or additives in the solution.3. Presence of other ions or additives: The CMC of SDS can be affected by the presence of other ions or additives in the solution. For example, the presence of electrolytes, such as sodium chloride NaCl , can decrease the CMC of SDS due to the screening effect of the counterions. This effect is known as the "salting-out" effect. On the other hand, the presence of additives that can form complexes with the surfactant, such as cyclodextrins, can increase the CMC.In summary, the CMC of SDS is around 8 x 10^-3 mol/L at room temperature and can be influenced by temperature, concentration of the solution, and the presence of other ions or additives. To determine the exact CMC of SDS under specific conditions, experimental measurements or literature data should be consulted.