From the data given for surface tension as a function of surfactant concentration at 30°C, calculate the CMC of the surfactant and the area occupied by a single molecule of the surfactant on the interface at full coverage.


Concentration (mM)
0
0.001
0.002
0.003
0.004
0.006
0.008
0.010
0.012
0.014
0.016
0.018
0.020
0.025

Surface tension (mN.m–1)
69.0
67.4
66.0
65.1
63.9
62.2
60.9
59.7
58.6
57.6
56.7
56.0
55.3
53.9