Interfacial Phenomena

Question 1

Mass of substance that possesses a well define boundary

Answer 1

Phase

Question 2

Occurs when molecules at the surface of the liquid experience an inward force toward the bulk

Answer 2

Surface tension

Question 3

Force per unit length that must be applied parallel to the surface so as to counterbalance the net inward pull

Answer 3

Surface tension

Question 4

SI unit for surface tension

Answer 4

N/m

Question 5

Cgs system unit for surface tension

Answer 5

Dynes/cm

Question 6

Force per unit length existing at the interface between two immiscible liquid phases

Answer 6

Interfacial tension

Question 7

Often used for the attractive forces between immiscible liquids

Answer 7

Interfacial tension

Question 8

Work done against surface tension to move molecules from the inner layers to the surface

Answer 8

Surface Free energy

Question 9

Measurement of surface and interfacial tensions

Answer 9

CDPSDWBO

Question 10

Choice of method of measurement depends on:

Answer 10

SASE

Question 11

T/F Inc temp inc surface tension

Answer 11

F

Question 12

Equation for capillary rise method

Answer 12

Y=rpgh

Question 13

T/F in capillary rise method, the force of adhesion of the liquid and the wall is less than the cohesion forces of liquid molecules

Answer 13

F

Question 14

Principle is that the force necessary to detach a platinum-iridium ring immersed at the surface or interface is proportional to the surface or interfacial tension

Answer 14

DuNouy Ring Method

Question 15

Equation used for the DuNuoy Ring method

Answer 15

Y=(dial reading/2xring circumference) x correction factor (beta)

Question 16

Free energy required to separate two phases at their boundary or to break the attraction between unlike molecules

Answer 16

Work of Adhesion

Question 17

Equation of work of adhesion

Answer 17

Wa=YL+Ys+ YLS

Question 18

Work required to separate molecules of the spreading liquid so that it can flow over the sublayer

Answer 18

Work of Cohesion

Question 19

When added molecules partitioned in favor of the bulk

Answer 19

Negative adsorption

Question 20

When added molecules are partitioned in favor of the interface

Answer 20

Positive adsorption

Question 21

Adsorbed at the interface to lower the interfacial tension between phases due to their amphiphilic nature

Answer 21

Surfactants

Question 22

0-3 HLB

Answer 22

Anti foaming

Question 23

7-9

Answer 23

Wetting agents

Question 24

3-8

Answer 24

Water in oil emulsifying agents

Question 25

8-16

Answer 25

Oil in water

Question 26

16-18

Answer 26

Solubilizing agents

Question 27

13-16

Answer 27

Detergents

Question 28

Amount of amphiphile per unit area of surface in excess of that in bulk of the liquid

Answer 28

Surface excess

Question 29

T/F the addition of amphiphile to a liquid system leads to a reduction in surface tension

Answer 29

T

Question 30

Factors that affect the adsorption of gas by a solid

Answer 30

chemical nature of adsorbent and adsorbate Surface area of adsorbent Temp Partial pressure of the adsorbed gas

Question 31

Irreversible interface unless the bonds are broken

Answer 31

Chemisorption

Question 32

Removal of adsorbate from adsorbent

Answer 32

Desorption

Question 33

Describes the relationship between the amount of gas physically adsorbed on the surface of the solid and the equilibrium pressure or concentration at constant temperature

Answer 33

Adsorption isotherm

Question 34

A plot of constant temperature

Answer 34

Isotherm

Question 35

Aids in displacing an air phase at the surrface, and replaces it with liquid phase

Answer 35

Wetting agent

Question 36

Angle which the liquid makes with the solid surface

Answer 36

Contact angle

Question 37

Contact angle = 0

Answer 37

Complete wetting

Question 38

Surfactants that are used for the removal of dirt

Answer 38

Detergents

Question 39

Initial wetting of the dirt and of the surface to be cleaned

Answer 39

Detergency

Question 40

Stable structure consisting of air pockets enclosed within films of liquid, the gas-in-liquid dispersion being stabilized by a foaming agent

Answer 40

Foam

Question 41

Agents as alcohol, ether, castor oil and some surfactants that break the foam

Answer 41

Antifoaming agents

Question 42

Other name for nernst potential

Answer 42

Electrothermodynamic potential

Question 43

Defined as the difference in potential between the actual surface and the electroneutral region of the surface

Answer 43

Nernst potential

Question 44

Other term for zeta potential

Answer 44

Electrokinetic potential

Question 45

Defined as the difference in potential between the surface of the tightly bound layer and the electroneutral region of the solution

Answer 45

Zeta potential

Question 46

Happens when the potential is reduced below a certain value, the attractive forces exceed the repulsive forces and the particles come together

Answer 46

Flocculation

Question 47

Boundary of separation of two phases

Answer 47

Interface