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DDS > 3.5 > Flashcards

3.5 Flashcards

1
Q

In emulsions, the simple oil/water mixture is homogenized, then, if a smaller particle size is desired, the homogenate is passed through a…

A

colloid mill

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2
Q

An emulsion can be reversibly or irreversibly altered by droplet aggregating and its possible sequelae, which includes …

A

coalescence (two droplets become one) and creaming (droplets rise to the top)

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3
Q

interfacial free energy is..

A

work done to increase the interfacial surface area

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4
Q

interfacial tension (liquids) is the _____, it measures the force to overcome in mixing two liquids

A

surface tension at the surface separating two immiscible liquids

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5
Q

To increase the interfacial surface area (dA) between water and oil, energy must be added to the system. This is equal to …

A

Interfacial free energy (dG)

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6
Q

To make emulsification easier is by (decreasing or increasing) interfacial tension, and that’s where surfactants play a role.

A

decreasing

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7
Q

The system free energy is reduced by the reduction of total surface area by (increasing or decreasing) particle size which gives rise to physical instabilities.

A

increasing

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8
Q

Coalesce is ____, and coalescence is from a physical stability point bad.

A

To grow or come together into one

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9
Q

When there is complete coalescence it is called complete phase separation, also referred to “____” of an emulsion and it is irreversible.

A

breaking

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10
Q

_____ results from flocculation and concentration of disperse phase (rise to the top)

A

creaming

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11
Q

Creaming is usually reversible (by agitation) but still not desirable since…

A

it is a step closer to phase separation and unappealing

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12
Q

(High or low) temperatures can accelerate droplet aggregation because ___ temperature increase droplet movement and collisions.

A

high

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13
Q

(Freezing or boiling) can concentrate the droplets, and drive one particle together to each other and separate from other particle.

A

freezing

water freezes separately

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14
Q

_____emulsifiers facilitate droplet formation, and emulsion _____ help prevent flocculation, coalescence, and creaming,

A

Surfactant; stabilizers

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15
Q

____ can be used as both surfactant emulsifier and emulsion stabilizer.

A

Acacia

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16
Q

In emulsions, _______ can absorb at the oil/water interface since they are amphiphilic, they have affinity for both phases.

A

Surfactant emulsifiers

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17
Q

Surfactant emulsifiers are surface active which means they (increase or decrease) interfacial tension

A

decrease

i.e. reduce force needed to mix immiscible liquids

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18
Q

_______ interfere with flocculation, coalescence, creaming, by forming barriers to aggregation and/or by altering the continuous phase.

A

Emulsion stabilizers

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19
Q

Ionic (electric repulsion) of surfactants does it by charge while the non-ionic does it by…

A

size of hydrophilic component

20
Q

Acacia is an example of ____, where it forms a stabilizing multimolecular film around the droplet

A

hydrophilic colloid

21
Q

____ similar to hydrophilic colloid in that they form a stabilizing (particulate) film around the droplet such as bentonite, veegum.

A

Finely divided solids

smaller than oil droplets

22
Q

You can prevent droplets from rising my (increasing or decreasing) viscosity

A

increasing

23
Q

HLB stands for ____, this system was devised to enable a rational means of surfactant selection for different formulation types.

A

hydrophilic-lipophilic balance

24
Q

(Higher or lower) the HLB, the Increased surfactant polarity which means increased hydrophilicity.

A

Higher

25
Q

High HLB, means the lipophilic groups is (larger or smaller) than the hydrophilic group.

A

smaller

26
Q

Tenet of HLB system: The phase in which the surfactant emulsifier is most soluble becomes the _____ phase of the emulsion.

A

continuous

27
Q

Emulsifiers with a relatively low HLB will form (w/o or o/w) emulsions.

A

w/o

28
Q

Emulsifiers with relatively high HLB will form (w/o or o/w) emulsion.

A

o/w

29
Q

As internal phase volume % increases this increase particle number which increase friction (more particles interaction with each other) and lead to

A

increase viscosity

30
Q

______ amount of internal phase, where if the internal phase volume percentage gets too high you may have a flip (from W/O to O/W) and vice versa.

A 
Phase inversion
(change of emulsion type)
31
Q

____- clear, thermodynamically stable – dispersions of two immiscible liquids containing appropriate amounts of surfactants, or surfactants and cosurfactants.

A

Micro-emulsions (clear, stable)

32
Q

The micro-emulsions formulation is such that the interfacial tension is transiently (negative or positive) (means emulsion forms spontaneously) and near zero after emulsion formation (means emulsion is nearly thermodynamically stable)

A

negative (negative dE or dG)

33
Q

Micro-emulsions are transparent since they are less than 0.1 microns and droplets are smaller than …

A

visible light wavelengths

34
Q

Smaller cosurfactants enable the _____ that allows micro-emulsions to exist.

A

curvature

35
Q

Avoid excess levigating agent because shear force will (increase or decrease) creating soup-like substance

A

decrease (you want it paste-like) but to maximize shear force

36
Q

When using viscous vehicles, first dissolve ingredients in a minimum quantity of ____ because it is difficult to dissolve substances in viscous vehicles (e.g. glycerol)

A

water

37
Q

Useful Tip in compounding Solutions: Add ____ viscosity liquids to ___ viscosity liquids with constant stirring.

A

high to low

38
Q

Useful tip in compounding elixir, dissolve components _____

A

Separately

(alcohol- soluble to alcohol
water-soluble to water)

39
Q

Levigate with water- (miscible or immiscible) levigating agent

A

water- miscible

40
Q

Dispense suspensions in appropriate containers with adequate _____ for shaking.

A

head space

41
Q

Storage temperature if too (high or low) crystals can dissolve, then recrystallize to a different size

A

high

42
Q

Storage temperature if too (high or low) can cause crystals to aggregate

A

low (aggregate if frozen)

43
Q

Wet gum (____) and Dry gum (continential)

A

english

44
Q

_____ (dry gum) and English (wet gum)

A

Continental

45
Q

Continental “dry gum” also known as the _____ method

A

4:2:1

4 parts oil: 2 parts water: 1 part gum

DDS (29 decks)

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