Surfactants are amphiphilic molecules that reduce the surface tension of water. They were first observed by J.W. Gibbs to concentrate at liquid surfaces more than in bulk solutions, as expressed by Gibbs' adsorption equation. Surfactants form micelles, spherical aggregates of surfactant molecules, above their critical micelle concentration in water. Examples of surfactants include stearic acid.

1. SURFACTANTS
BY : PRANAV DALVI
RUDRANSHI
OM PATIL

2. SURFACTANTS
 Surface-active agents
 Amphiphilic in water
 Reduces surface tension of water
 e.g. :stearic acid CH3-(CH2)16-COOH

3. GIBBS ADSORPTION EQUATION
• It was observed by J.W. Gibbs (1878) that the concentration of a solute at
surface of a liquid could be greater than in the bulk of the solution
• The thermodynamic relation expressing this behaviour is referred to as
Gibbs adsorption equation . For a dilute solution ,this equation is,
• 𝑠 = −
𝑐
𝑅𝑇
ⅆ𝛾
ⅆ𝑐
• Where S is the excess concentration of solute per unit area of the surface
as compared with the bulk of the solution , c is the concentration of the
solution,
ⅆ𝛾
ⅆ𝑐
is the rate of variation of surface tension of solution with
concentration of the solute , R is the molar gas constant and T is the
absolute temperature

4. STRUCTURE OF SURFACTANTS AND CMC
• When a surfactant is
placed in water it
forms micelle at
concentration above
its critical
micelle(CMC) they
forms aggregates
known as micelles

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