Exercise
To be submitted by Feb 7 (option)
1. The surface tension of liquid sodium at 100 C is 220 ergs/cm2, and its contact angle
with glass is 660. (a) Estimate, with explanation of your procedure, the surface tension
of glass at 100C. (b) If given further that the surface tension of mercury at 100C is
460 ergs/cm2 and that its contact angle with glass is 1430, estimate the surface tension
of the glass.
2. The contact angle of water on paraffin is 1110 at 25C. For 0.1M solution of
butylamine of surface tension 56.3 mJ/m2, the contact angle was 920. Calculate the
film pressure of the butylamine adsorbed at the paraffin-water interface. State any
assumptions that are made.
3. The adsorption energy per organo-thiol molecule on gold substrate is 1 eV. The
area per adsorbed molecule is 30 Ǻ2. What is the highest dipole moment the molecule
can have perpendicular to the surface, so that a closed packed layer will still be
formed. What will be the effect of the temperature on the maximum dipole moment ?
Explain the assumptions you made.