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.