Exercise 7: Surface Tension ❤
dA = YdO
At constant volume and temperature, the work of surface formation can be identified with the change in A (maximum work function).
Only one
At critical Temperature, liquid and vapor interface disappears and ______ phase is present.
Cohesion
Attractive forces operating between like molecules.
Adhesion
Attractive forces operating between unlike molecules.
Surface Excess or activity of solute
Due to unequal distribution of solute between the surface and the body of solution.
NTAP, Nature of liquid, temperature, added solute, pressure,
Factor Affecting Surface Tension
Lower
Higher Temperature produce ______ surface Tension.
Lower Surface Tension
Higher pressure will result _____.
ECAPM is positive
Increase Surface tension
Surface Tension
Natural tendency of the liquid surface to behave like a stretched elastic membrane wherein surface area is minimized.
Katayama Constant, K
Relates the change in the product of the surface tension and molar volume with temperature.
Molecules at the surface of a liquid
Resultant inward attraction
Negative Surface Excess
Solute stays more at the bulk, higher Surface Tension.
Positive Surface Excess
Solute stays more at the surface. Lower Surface Tension. Example, polar molecules
Higher Surface Tension
Stronger IMFA suggest more curved surface which means ______.
A, G
Surface effects may be expressed thermodynamically in terms of these
dA < 0, dO < 0
Surface have a natural tendency to contract.
ECAPM is negative
Surface tension is decrease
Molecules at the interior of a liquid
Surrounded completely by other molecules that has equal attraction in all directions.
Minimum area
Unbalanced forces of attraction at the surface, liquid surface tends to contract inward at its _____.
dW = YdO
Work needed to change the surface area (O) of a sample by infinitesimal amount (dO).
ECAPM
suggests an increase or decrease in surface area with addition of solute.