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PHYPHARM > INTERFACIAL PHENOMENA > Flashcards

INTERFACIAL PHENOMENA Flashcards

1
Q

a boundary between two states of matter

A

INTERFACE

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2
Q

Pharmaceutical dispersions having 2 or more phases

A

heterogenous system

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3
Q

gas-gas interface is ___

A

impossible

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4
Q

Boundary of gas-solid or gas-liquid

A

SURFACE

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5
Q

solid particles dispersed into a liquid

A

SUSPENSION

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6
Q

drug-containing liquid is dispersed as droplets into an immiscible liquid

A

EMULSIONS

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7
Q

every surface is an ____

A

INTERFACE

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8
Q

significant factors that affect adsorption of drugs

A

Interfacial phenomena in pharmacy & medicine

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9
Q

formed between two phases

A

INTERFACIAL PHASE

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10
Q

affect drug delivery systems

A

INTERFACIAL PHENOMENA

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11
Q

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

A

SURFACE TENSION

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12
Q

Units of surface & interfacial tension

A

dynes/cm or N/m

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13
Q

Force per unit length existing at the interface of two immiscible liquids

A

INTERFACIAL TENSION

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14
Q

γ

A

suface tension

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15
Q

γLL γLS γSS

A

interfacial tension

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16
Q
  • Most accurate method (liquid is undisturbed)
  • For surface tension ONLY
A

CAPILLARY RISE METHOD

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17
Q

formula for capillary rise method

A

γ = 1/2 rℎρg

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18
Q

Principle:
* The force necessary to detach a Platinum-Iridium ring immersed at the surface or interface

A

Du Noűy Ring Method

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19
Q
  • Widely used for measuring surface and interfacial tensions
A

DuNoűy Tensiometer

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20
Q

particle size between greater than 500 nm (0.5 μm)

A

coarse dispersions

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21
Q

when the size of the dispersed particles is 1 to 500 nm

A

colloidal dispersion

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22
Q

dispersion medium

A

External or continuous phase

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23
Q

dispersed phase

A

internal phase

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24
Q

Basic objective in the formulation

A

stable interfaces

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25
Q

The condition in which the particles do not aggregate and which they remain uniformly distributed throughout the dispersion.

A

PHYSICAL STABILITY

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26
Q

A bounded space or an exact quantity of a material

A

system

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27
Q

Consists of at least two phases with one or more dispersed phase (internal) contained in a single continuous (external) phase

A

DISPERSION

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28
Q

A distinct homogenous part of a system

A

phase

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29
Q

oil and water interface

A

liquid-liquid

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30
Q

interface between the suspended solid particle and the suspending medium

A

solid-liquid

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31
Q

Attraction between like molecules

A

COHESIVE FORCES

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32
Q

Attraction between unlike molecules

A

ADHESIVE FORCES

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33
Q

what happens to the interfacial tension & surface tension when the cohesive attraction between molecules of like phases is greater than the adhesive attraction of unlike molecules found in the bulk phase

A

INTERFACIAL & SURFACE TENSION INCREASES

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34
Q

what happens to the interfacial tension & surface tension when the adhesive attraction is greater than the cohesive attraction

A

interfacial & surface tensions decreases

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35
Q

PHASE

Liquid surface, body of water exposed to atmosphere

A

GAS-LIQUID

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36
Q

PHASE

Solid surface, table top

A

gas-solid

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37
Q

PHASE

emulsion

A

liquid-liquid

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38
Q

PHASE

suspension

A

liquid-solid

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39
Q

PHASE

powder particles in contact

A

solid-solid

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40
Q

occurs due to unbalanced cohesive forces at the interface of a liquid and a gas or at the interface of two liquids

A

SURFACE TENSION

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41
Q

must be done against the force of surface tension to move a molecule from the inner layers to the surface

A

WORK

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42
Q

the molecules ____ of a liquid possess an excess of potential energy compared to the molecules in the bulk

A

near the surface

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43
Q

Molecules near the surface of liquids possess ____ as compared to molecules located at the bulk of the liquid

A

excess potential energy

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44
Q

Molecules near the surface of liquids possess excess potential energy as compared to molecules located at the bulk of the liquid

A

SURFACE FREE ENERGY

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45
Q

energy is ____ to the size of the free
surface

A

PROPORTIONAL

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46
Q

energy is proportional to the size of the free surface

A

SURFACE FREE ENERGY

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47
Q

more molecules will have this excessive potential energy if the surface of the liquid is ____

A

HIGHER

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48
Q

if the surface of the liquid increases, what will happen to the energy of the liquid

A

increases

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49
Q

Are surface active agents or surfactants (emulsifying agents)

A

AMPHIPHILES

50
Q

head of amphiphiles

A

hydrophilic, polar

51
Q

tail of amphiphiles

A

lipophilic, nonpolar

52
Q

materials that increase surface area of dispersed phase with the dispersion medium by:
* Lower the surface tension or interfacial between two liquids or between a liquid and a solid
* Lower surface free energy

A

SURFACTANTS

53
Q

causes immiscible phases to resist mixing and shrink their surfaces

A

interfacial or surface tension

54
Q

Which is higher, surface tension or interface tension?

A

surface tension

adhesive attraction between liquid and gas interface or surface is weaker than the adhesive attraction between liquid and liquid interface

55
Q

what is necessary to control in the system when carrying out surface and interfacial tension determination

A

TEMPERATURE

56
Q

At the critical temperature, surface tension becomes

57
Q

surface tensions of most liquids ____ within an increase in temperature

58
Q

work that must be done to increase surface area

A

Surface free energy

59
Q

What should be to increase surface area?

A

Reduce surface free energy and surface/interfacial tension

60
Q

the addition of molecules that moves to the interface.

A

positive adsorption

61
Q

the addition of molecules that moves to the bulk portion

A

negative adsorption

62
Q
  • a surfactant with a negative charge
  • an example is sodium lauryl sulfate
  • These surfactants are widely used in cosmetics and pharmaceutical industries; though they have an unpleasant taste and some have skin irritation properties.
A

anionic surfactants

63
Q
  • a surfactant with a positive charge
  • an example is dodecyl ammonium chloride
  • Most widely used are the quaternary ammonium compounds.
A

Cationic surfactants

64
Q
  • not electrolytes
  • their surface-active portion has no charge
  • an example is the sorbitan fatty esters.
A

nonionic surfactants

65
Q
  • are zwitterions that have both positive and negative charges
  • an example is alkyl betaines.
A

amphoteric surfactants

66
Q

In the general sense, any material that affects the interfacial surface tension can be considered a

A

surfactant

67
Q

in the practical sense, ____ may act as wetting agents, emulsifiers, foaming agents, and dispersant

A

surfactants

68
Q

Used to classify surfactants

A

HLB system

69
Q
  • Classifies the non-polar and polar nature of the emulsifier
  • The balance of the hydrophilic and lipophilic properties of an emulsifying agent or emulsifier determines whether an O/W or W/O emulsion will result.
A

hydrophile-lipophile balance

70
Q

the presence of a greater concentration of a material at the surface than is present at the bulk

A

ADSORPTION

71
Q
  • involves strong bonds
  • typically irreversible
  • can only form monolayers
A

chemisorption

72
Q
  • involves the penetration of the substance into the inner structure
  • involves the passage of a drug across a barrier membrane
A

ABSORPTION

73
Q

it is called ____ if a substance is adsorbed to the surface and absorbed into the bulk

74
Q

Substances with part of their molecule lipophilic and part hydrophilic move on their own to the surfaces or interfaces of the liquid.

A

surface active ingredients

75
Q

amphiphiles having high HLB values

A

HYDROPHILIC

76
Q

water-loving

A

HYDROPHILIC

77
Q

amphiphiles are having low HLB values

A

LIPOPHILIC

78
Q

The type of emulsion is a function of the relative solubility of the surfactant, the phase in which it is more soluble being the continuous phase.

A

BANCROFT RULE

79
Q

Emulsifier with a ____ HLB value is soluble in water and results in the formation of an o/w emulsion

80
Q

Emulsifier with a high HLB value is soluble in water and results in the formation of an ____ emulsion

81
Q

emulsifier with high HLB value is soluble in

82
Q

Emulsifier with ____ HLB value are soluble in oil and forms a w/o emulsions

83
Q

Emulsifier low HLB value are soluble in oil and forms a ____ emulsions

84
Q

Emulsifier with Low HLB value are soluble in

85
Q

high HLB values

HYDROPHILIC SURFACTANTS

86
Q

low HLB values

LIPOPHILIC SURFACTANTS

87
Q

what do u call low HLB values (3-6) that forms W/O emulsifying agents

88
Q

what do u call HIGH HLB values (8-16) that forms O/W emulsifying agents

89
Q

HLB formula

A

HLB = 20 (1-S/A)

s = saponification no (ester)
a = acid number (fatty acid ester)

90
Q

Takes place from either adjacent liquid or gas phase

A

ADSORPTION AT SOLID INTERFACES

91
Q

concerned with the following:
● Removal of objectionable odor from room and food
● Operation of a gas mask
● Measurement of particle dimension of powders

A

adsorption of GASES at the SOLID

92
Q

concerned with the following:
● Decolorizing solution
● Absorption chromatography
● Detergency and wetting

A

Adsorption of liquid at solid interfaces

93
Q

The Solid-Gas Interface depends on:

the material used to adsorb the gas

94
Q

The Solid-Gas Interface depends on:

the substance being adsorbed

95
Q

TYPES OF ADSORPTION

➢ this adsorption is reversible, is the removal of the adsorbate from the adsorbent known as desorption (an increase of temperature and reduced pressure).
➢ The adsorbate can be removed from the adsorbent by increasing the temperature
(Desorption)

A

Physical adsorption or van der Waals adsorption

96
Q

Physical adsorption is also known as

A

van der waals adsorption

97
Q

removal of adsorbate from the adsorbent

A

DESORPTION

98
Q

➢ adsorbate is attached to the adsorbent by primary chemical bonds, is irreversible unless the bonds are broken.
➢ Activated charcoal – a substance that can absorb enormous amounts of gases or liquids. It is the residue from the destructive distillation of various organic materials, treated to increase its adsorptive powers.

A

Chemical adsorption or chemisorption

99
Q

FACTORS AFFECTING ADSORPTION

The extent of adsorption of a solute is inversely proportional to its solubility in the solvent from which adsorption occurs.

A

SOLUBILITY OF THE ADSORBATE

100
Q

FACTORS AFFECTING ADSORPTION

Adsorption increases as the ionization of the drug is suppressed.

101
Q

FACTORS AFFECTING ADSORPTION

The extent of adsorption is proportional to the specific surface area.

A

NATURE OF ADSORBENT

102
Q

FACTORS AFFECTING ADSORPTION

An increase in temperature decreases the amount of adsorbed

A

TEMPERATURE

103
Q

Principles that uses solid/liquid adsorption

A complex process involving the removal of foreign matter from surfaces.

A

DETERGENCY

104
Q

are surfactants that are used for the removal of dirt.

A

DETERGENTS

105
Q

a surfactant that when dissolved in water, lowers the advancing contact angle and aids in displacing an air phase at the surface and replacing it with a liquid phase.

A

WETTING AGENT

106
Q

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

A

CONTACT ANGLE

107
Q

Detergents and soaps have the property called ____ which is a complex process of removing dirt.

A

DETERGENCY

108
Q

a stable structure consisting of air pockets enclosed within thin films of liquid

109
Q

the gas-in-liquid dispersion being stabilized by a

A

FOAMING AGENT

110
Q

break foam, examples are alcohol, ether, castor oil, and some surfactants.

A

ANTIFOAMING AGENTS

111
Q

potential at the solid surface due to potential determining ion. It is the difference in potential between the surface and the electroneutral region of the solution

A

Electrothermodynamic (Nernst) potential, E

112
Q

is the difference in potential between the surface of the tightly bound layer and the electroneutral region of the solution.

A

Electrokinetic or Zeta potential

113
Q

Low zeta potential values lead to ____

A

FLOCCULATION

114
Q

What is the dynes per cm existing at the interface between oil and water?

A

INTERFACIAL TENSION

115
Q

TRUE OR FALSE

Spans and tweens increase surface free energy

116
Q

TRUE OR FALSE

Hydrophilic surfactants have low HLB values while lipophilic surfactants are having high HLB values

117
Q

TRUE OR FALSE

The greater is the adhesive attraction between 2 immiscible liquids, the lesser is the interfacial tension

118
Q

TRUE OR FALSE

Amphiphiles in oil-in-water emulsion will have polar heads out and in water-in-oil emulsion will have polar heads in

119
Q

TRUE OR FALSE

Emulsifier with a high HLB value is soluble in water and results in the formation of an o/w emulsion

120
Q

The addition of these particles will reduce the interfacial tension and produce a more stable heterogeneous mixture

A

AMPHIPHILES /
SURFACTANTS /
SURFACE ACTIVE INGREDIENTS

PHYPHARM (28 decks)

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