1. Experiment (10):Determination of Critical Micelle Concentration (CMC) Theory
Surfactants, sometimes called Surface active substances (SAS) are amphiphilic materials containing both a non polar long- chain hydrocarbon “tail” and polar, usually ionic, “head” groups.
Fig. (10.1) : Spherical micelle of sodium dodecyl sulfate

2. Types of Surfactants: 
Depending on the chemical structure of the surfactants can be classified into four types:
1-Cationic: Dodecylamine hydrochloride, Hexadecyltrimethyl ammonium bromide,
2-Anionic: Sodium stearate, sodium dodecyl benzene sulphonate, …
3-Ampholitic (Zwitteriionic): Dodecyl betaine
4-Non ionic: Tweens, Triton X-100

4. Critical micelle concentration, (CMC): The concentration (actually an arbitrary concentration within a narrow range) above which micelles form. Experimentally, the CMC is found by plotting a graph of a suitable physical property as a function of surfactant concentration. An abrupt change of slope marks the CMC.

5. Object To determine CMC of SDS by conductivity Procedure
1-Prepare a stock solution of M of SDS of volume 50 mL of the surfactant (given by the instructor).
2- From the stock solution, prepare the following a series of dilute solutions: (50 ml each) , 0.008, 0.01, 0.015, M
3-By using the conductivity meter, measure the specific conductivity (K) in S cm-1.