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PH 108 - Physical Pharmacy (Lec) > Interfacial Phenomena and Coarse Dispersion > Flashcards

Interfacial Phenomena and Coarse Dispersion Flashcards

1
Q

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

A

Interfaces

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2
Q

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

A

Surface

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3
Q

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

A

Interfacial tension

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4
Q

2 surface and interfacial tensions unit

A

dynes/cm, N/m

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5
Q

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

A

Spreading coefficient

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6
Q

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

A

Work of adhesion

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7
Q

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

A

Work of cohesion

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8
Q

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

A

Solubilization

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9
Q

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

A

Emulsion

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10
Q

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

A

Oil-in-water (o/w)

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11
Q

Type of emulsion where the oil is the continuous phase

A

Water-in-oil (w/O)

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12
Q

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

A

Liposome formulations

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13
Q

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

A

Nanoemulsions

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14
Q

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

A

Microemulsions

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15
Q

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

A

Emulsifier

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16
Q

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

A

Surface-active agents

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17
Q

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

A

Hydrophilic colloids

18
Q

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

A

Finely divided solid particles

19
Q

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

A

Monomolecular adsorption

20
Q

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

A

Hydrated lyophilic colloids

21
Q

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

A

Solid-particle adsorption

22
Q

2 types of adsorption

A

Physical adsorption, Chemical adsorption

23
Q

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

A

Physical adsorption

24
Q

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

A

Chemical adsorption

25
Q

The removal of the adsorbate from the adsorbent

A

Desorption

26
Q

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

A

Adsorption isotherm

27
Q

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

A

Contact angle

28
Q

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

A

Wetting agent

29
Q

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

A

Potential-determining ions

30
Q

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

A

Counterions, Gegenions

31
Q

Is the surface of the solid

A

aa’

32
Q

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

A

bb’

33
Q

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

A

Nernst and Zeta potentials

34
Q

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

A

Electrothermodynamic (Nernst) potential (E)

35
Q

The potential located at the shear plane (bb’)

A

Electrokinetic (Zeta) potential (ζ)

36
Q

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

A

Zeta potential

37
Q

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

A

Suspension

38
Q

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

A

Flocculated particles

39
Q

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

A

Deflocculated particles

40
Q

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

A

Degree of flocculation (β)

41
Q

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

A

Electrolytes

42
Q

Added to retard sedimentation of the flocs

A

Suspending agents

PH 108 - Physical Pharmacy (Lec) (8 decks)

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