Reference no: EM13589114

(a) The following surface tension were measured for aqueous solutions of the nonionic surfactant

CH₃(CH₂)₉(OCH₂CH₂)₅OH at 25°C

C(10-4mol/dm-3)   0.1    0.3    1.0    2.0   5.0    8.0    10.0   20.0   30.0
γ (mN/m)              63.9   56.2  47.2  41.6  34.0  30.3  29.8  29.6    29.5

Determine the critical micelle concentration and calculate the area occupied by each adsorbed surfactant molecule at the critical micelle concentration.

(b) The critical micelle concentration of nonionic surfactant in water varies with temperature as follows:

Temperature (oC)   15      20     25     30       40
CMC (mmol/dm3)   21.9   20.8  19.9   19.1  17.8

Determine an enthalpy of micellization according to the phase separation model.