FINAL 01 - Interfacial Phenomena and Coarse Dispersion

Question 1

When phases exist together, the boundary between two of them is known as __________

Answer 1

Interfaces

Question 2

The term __________ is used when referring to either a gas-solid or a gas-liquid interface

Answer 2

Surface

Question 3

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

Answer 3

Interfacial tension

Question 4

2 surface and interfacial tensions unit

Answer 4

dynes/cm, N/m

Question 5

Is the difference between the work of adhesion and the work of cohesion

Answer 5

Spreading coefficient

Question 6

Is the energy required to break the attraction between the unlike molecules

Answer 6

Work of adhesion

Question 7

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

Answer 7

Work of cohesion

Question 8

The ability of the micells to increase the solubility of materials that are normally insoluble, or only slightly soluble, in the dispersion medium used

Answer 8

Solubilization

Question 9

A thermodynamically unstable system containing two immiscible liquid phases stabilized by emulsifying agent

Answer 9

Emulsion

Question 10

Type of emulsion used mainly for internal/oral use as bitter or disagreeable taste and odor of drugs can be masked by emulsification

Answer 10

Oil-in-water (o/w)

Question 11

Type of emulsion where the oil is the continuous phase

Answer 11

Water-in-oil (w/O)

Question 12

Type of emulsion which involves colloidal systems consisting of vesicle forming phospholipids and water

Answer 12

Liposome formulations

Question 13

Type of emulsion which involves colloidal systems consisting of vesicle forming phospholipids, surfactants, and lipids dispersed in water

Answer 13

Nanoemulsions

Question 14

Type of emulsion which involves a colloidal semi-liquid o/w or w/o emulsion systems consisting of a complex mixture of lipo- and hydrophilic surfactants and water

Answer 14

Microemulsions

Question 15

Are amphiphilic compounds; stabilizer of the droplet form of the internal phase

Answer 15

Emulsifier

Question 16

Are adsorbed at oil-water interfaces to form mononuclear films and reduce interfacial tension

Answer 16

Surface-active agents

Question 17

Form a multi-molecular film around the dispersed droplets of oil in an o/w emulsion

Answer 17

Hydrophilic colloids

Question 18

Are adsorbed at the interface between two immiscible liquid phases and form what amounts to a film of particles around the dispersed globules

Answer 18

Finely divided solid particles

Question 19

Theory of emulsification that states that surface-active agents or amphiphiles, reduce interfacial
tension because of their adsorption at the oil-water interface to
form monomolecular films

Answer 19

Monomolecular adsorption

Question 20

Are surface active agents (oil-water interface); differ from synthetic surface active agents

Answer 20

Hydrated lyophilic colloids

Question 21

Theory of emulsification that states that finely divided solid particles that are wetted to some degree by both oil and water can act as emulsifying agents

Answer 21

Solid-particle adsorption

Question 22

2 types of adsorption

Answer 22

Physical adsorption, Chemical adsorption

Question 23

Type of adsorption where a physically adsorbed gas can be desorbed from a solid by increasing the temperature and reducing the pressure

Answer 23

Physical adsorption

Question 24

Type of adsorption where the adsorbate is attached to the adsorbent by primary chemical bonds

Answer 24

Chemical adsorption

Question 25

The removal of the adsorbate from the adsorbent

Answer 25

Desorption

Question 26

The relationship between the amount of gas physically adsorbed on a solid and the equilibrium pressure pressure or concentration at constant temperature yields an __________ when plotted

Answer 26

Adsorption isotherm

Question 27

Is the angle between a liquid droplet and the surface over which it spreads

Answer 27

Contact angle

Question 28

Is a surfactant that, when dissolved in water, lowers the advancing contact angle

Answer 28

Wetting agent

Question 29

The adsorbed ions that give the surface its positive charge are referred to as the __________

Answer 29

Potential-determining ions

Question 30

The ions, having a charge opposite to that of the potential-determining ions, are known as __________ or __________

Answer 30

Counterions, Gegenions

Question 31

Is the surface of the solid

Answer 31

aa'

Question 32

The limit of the region of tightly bound solvent molecules, together with some negative ions, also tightly bound to the surface

Answer 32

bb'

Question 33

Is defined as the difference in potential between the actual surface and the electroneutral region of the solution

Answer 33

Nernst and Zeta potentials

Question 34

The potential at the solid surface aa' due to the potential-determining ion is the __________

Answer 34

Electrothermodynamic (Nernst) potential (E)

Question 35

The potential located at the shear plane (bb')

Answer 35

Electrokinetic (Zeta) potential (ζ)

Question 36

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

Answer 36

Zeta potential

Question 37

A course dispersion in which insoluble solid particles are dispersed in a liquid medium

Answer 37

Suspension

Question 38

Are particles in a suspension that are weakly bonded, settle rapidly, do not form a cake, and are easily resuspended

Answer 38

Flocculated particles

Question 39

Are particles in a suspension that settle slowly and eventually form a sediment in which aggregation occurs

Answer 39

Deflocculated particles

Question 40

Is the ratio of the sedimentation volume of the flocculated suspension to the sedimentation volume of the suspension when deflocculated

Answer 40

Degree of flocculation (β)

Question 41

Acts as flocculating agents by reducing the electric barrier between the particles

Answer 41

Electrolytes

Question 42

Added to retard sedimentation of the flocs

Answer 42

Suspending agents