Emulsions (exam 2)

Question 1

emulsion

Answer 1

mixture of two or more immiscible liquids

Question 2

in a emulsion, liquids are made miscible by using

Answer 2

emulsifying agents

Question 3

emulsion is a ________________

the dispersed phase is _________________

dispersion medium is ________________

Answer 3

two phase system

internal phase

external/continuous phase

Question 4

advantages of emulsions

Answer 4

stable and homogenous
good palatability of distasteful oil
small oil globules more digestible and absorbed
less irritation on skin

Question 5

liquid emulsions

Answer 5

oral
topical
parenteral

Question 6

semi solid emulsions

Answer 6

topical

Question 7

O/W (oil in water) emulsion

Answer 7

internal phase - oil
external phase - water

Question 8

W/O (water in oil) emulsion

Answer 8

internal phase - aqueous
external phase - oil

Question 9

emulsifiers favor a particular ________________ and form either _______________ emulsions

Answer 9

emulsion type

w/o or o/w

Question 10

the phase presenting in the greater concentration tends to be

Answer 10

the external phase

Question 11

emulsifiers can overcome

Answer 11

an unfavorable phase ratio

Question 12

the phase that is being added tends to be the

Answer 12

external phase

Question 13

inversion of emulsions occurs when

Answer 13

emulsion prepared by heating is cooled
volume of internal or external phase changes

Question 14

emulsions are

Answer 14

physically unstable

Question 15

creaming

Answer 15

migration of droplets of the internal phase to the top or bottom of the emulsion

Question 16

flocculation

Answer 16

small spheres of oil stick together to form flocs, but the drops remain separated

Question 18

coalescence

Answer 18

merging of small droplets into larger droplets

Question 19

breaking is ______________ combined

Answer 19

coalescence and creaming

Question 20

breaking

Answer 20

oil separates completely from the water so it floats at top in a single, continuous layer

Question 21

which processes are reversible?

irreversible?

Answer 21

creaming and flocculation

breaking and sometimes flocculation

Question 22

Surface tension theory

Answer 22

tendency of liquids to have minimal surface area
if drops come into contact, they join

Question 23

emulsifiers facilitate the breakup of large globules by

Answer 23

lower the interfacial surface tension
reduce repellant force
diminish liquids attraction for its own molecules

Question 24

oriented wedge theory

Answer 24

molecular layer of emulsifying agent is curved around a droplet of internal phase based on hydrophilic/hydrophobic parts

Question 25

plastic or interfacial film theory

Answer 25

emulsifier surrounds the droplets of internal phase as a thin layer or film prevents contact and join of internal phase

Question 26

two step process of emulsification

Answer 26

lowering interfacial tension formation of protective wedge film around droplet

Question 27

an emulsifier concentrates at

Answer 27

the interface of two immiscible phases

Question 28

emulsifying agent with relatively strong hydrophilic group produces a

Answer 28

O/W emulsion

Question 29

emulsifying agent with relatively strong hydrophobic group produces a

Answer 29

W/O emulsion

Question 30

examples of emulsifiers

Answer 30

surfactants stabilizers thickeners

Question 31

surfactants can function as

Answer 31

solubilizers wetting agents flocculating agent emulsifying agent

Question 32

anionic surfactants

Answer 32

at pH over 8 soaps and sulfonates

Question 33

cationic surfactants

Answer 33

at pH 3-7 benzalkonium chloride

Question 34

nonionic surfactants

Answer 34

at pH 3-10 sorbitan esters polyoxyethylene derivatives

Question 35

a surfactant that produces an unstable emulsion (_______________), should be used in combination with a second substance (____________________) which stabilizes the product

Answer 35

primary emulsifier stabilizer, secondary emulsifier

Question 36

high molecular weight alcohol stabilizers

Answer 36

sterile alcohol cetyl alcohol cholesterol and derivatives

Question 37

colloidal clays stabilizers

Answer 37

magnesium hydroxide aluminum hydroxide bentonite

Question 38

carbohydrate thickeners

Answer 38

acacia pectin tragacanth agar microcrystalline cellulose

Question 39

protein thickeners

Answer 39

gelatin egg yolk casein

Question 40

emulsifier should have HLB value similar to

Answer 40

external or internal phase

Question 41

hydrophilic emulsifiers (o/w) HLB value

Answer 41

8-18

Question 42

lipophilic emulsifiers (w/o) HLB value

Answer 42

3-6

Question 43

methods to prepare emulsions

Answer 43

continental or dry gum method English or wet gum method bottle or Forbes bottle method

Question 44

4:2:1 method

Answer 44

4 parts oil 2 parts water 1 part gum

Question 45

order of mixing for dry gum method

Answer 45

1 part gum --> 4 parts oil --> 2 parts water

Question 46

order of mixing for wet gum method

Answer 46

1 part gum --> 2 parts water --> 4 parts oil

Question 47

Forbes bottle method is used for emulsions of

Answer 47

volatile oils or oils with low viscosity

Question 48

microemulsions

Answer 48

stable, transparent emulsions rapid absorption (oral/transdermal) diameter of droplets is small

Question 49

most _________ undergo oxidation, so a ___________ is needed

Answer 49

oils antioxidant or chelating agent

Question 50

chelating agents

Answer 50

organic compounds that form complexes with metal ions and inactive oxidation process

Question 51

auxiliary label for emulsions

Answer 51

container must be tightly closed shake well

Question 52

antioxidants for aqueous systems

Answer 52

ascorbic acid sodium bisulfate, metabisulfite sodium thiosulfate

Question 53

antioxidants for oil systems

Answer 53

ascorbyl palmitate butylated hydroxytoluene tocopherol sulfur dioxide

Question 54

chelating agents examples

Answer 54

edetic acid edetate disodium calcium disodium edetate citric acid

Question 55

emulsions should be protected from

Answer 55

freezing excessive heat oral in the fridge external at room temp