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Pharmaceutics II Exam 1 > Part 5 - Surfactants > Flashcards

Part 5 - Surfactants Flashcards

1
Q

define surface free energy

A

the work that must be done to increase the surface area

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2
Q

differentiate between positive adsorption and negative adsorption

A

in positive adsorption, the added molecules partition in favor of the INTERFACE to reduce the surface free energy and surface tension (SURFACTANTS)

in negative adsorption, the added particles partition in favor of the BULK to INCREASE the surface free energy and surface tension

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3
Q

give 2 examples of substances that exhibit positive adsorption (are surfactants)

A

fatty alcohol and fatty acid

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4
Q

give examples of substances that exhibit negative adsorption

A

inorganic electrolytes (NaCl)

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5
Q

true or false

inorganic electrolytes are not surfactants

A

true

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6
Q

differentiate between absorption and adsorption

A

adsorption is done solely on a solid surface (alkaloid molecules concentrating on the surface of a clay)

absorption – penetrating into the capillary spaces of the absorbing medium
(ie: water taken up into sponge)

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7
Q

if something has free energy, it is stable

A

false

unstable.

the purpose of a surfactant is to keep the free energy in the particles to keep their size small.

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8
Q

Surfactants _____ surface free energy and ______ surface tension

A

surfactants REDUCE surface free energy and REDUCE surface tension

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9
Q

most surfactants are _____

A

ampiphiles

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10
Q

amyl alcohol is how many carbons

A

5

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11
Q

cetyl alcohol is how many carbons

A

16

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12
Q

what does ampiphile mean? give example

A

ampiphile represents most surfactants.
it is molecules that have a certain affinity for both POLAR and NONPOALR solvents

hydrophilic – amyl alcohol

lipophilic (oil loving) – cetyl alcohol

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13
Q

surface active agents are ___ and ____ absorbed at _____

A

molecules and ions absorbed at interfaces

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14
Q

true or false

surfactants adsorb to surfaces, but not to interfaces

A

false – they adsorb to both

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15
Q

surfactants can also be used as what 3 things?

A

wetting agents
detergents
emulsifying agents

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16
Q

give 6 examples of surfactants

A

benzalkonium chloride
nonoxynol 10
octoxynol 9
polysorbate 80
sodium lauryl sulfate
sorbitan monopalmitate

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17
Q

The higher the HLB value of a surfactant, the more ____ it is

A

hydrophilic

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18
Q

what does HLB stand for? what does it mean?

A

HLB = hydrophilic-lipophile balance

arbitrary scale of values as a measure of surfactant

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19
Q

the lower the HLB value, the more ____ it is

A

lipophilic

20
Q

between Tweens and Spans, which are hydrophilic and which are lipophilic?

A

hydrophilic = tweens

lipophilic = spans

21
Q

the ______ energy, the more surfactant needed

A

more

22
Q

the HLB scale ranges from ___ to ____

A

0-18

23
Q

name all 6 agents on the HLB scale, in order from highest HLB to lowest HLB

A

solubilizing agents (16-18)
Detergents (13-16)
O/W Emulsifying agents (8-16)
Wetting and spreading agents (7-9)

W/O emulsifying agents (3-8)
most antifoaming agents (1-3)

24
Q

explain how transdermal patches work.

A

w/o emulsifying agent (HLB 3-8)

carries a water soluble compound within an oil droplet so it can cross the stratum corneum of the skin

25
Q

when are wetting agents used?

A

liquid-solid preparations (suspensions)
to reduce the particle size and get rid of overlying air above the particles

26
Q

reducing the particle size _____ the concentration at the absorption site and _____ bioavailability

A

increases conc at absorption site and increases bioavailability

27
Q

give an example of a soluble monolayer.
does it have a high or low HLB value?

A

amyl alcohol on water
high HLB value

28
Q

give an example of an insoluble monolayer

A

cetyl alcohol on water

29
Q

the material used to adsorb the gas in a solid-gas interface

A

adsorbent

30
Q

the substance being adsorbed in a solid-gas interface

A

adsorbate

31
Q

physical adsorption is via what mechanism? is it reversible or irreversible?

A

van der waals
reversible (can do desorption)

32
Q

give an example of chemical adsorption.
is it reversible or irreversible?

A

irreversible

used in bathroom odor remover

33
Q

give 3 examples in which solid-gas interfaces are applied in pharmaceutics

A

-removal of odors from a room
-gas masks
-moisture uptake by solids

34
Q

true or false

an N95 mask is a gas mask

A

FALSE

N95 mask is done via filtration

gas masks use adsorption (solid-gas interface) so we dont breathe the gas in

35
Q

name 4 factors that affect adsorption at solid-gas interfaces

A

-chemical nature of the adsorbent (solid) and adsorbate (gas)

-surface area of the adsorbent

-temperature

-partial pressure of the adsorbed gas

36
Q

true or false

adsorption at solid-gas interface is not dependent on the environment

A

FALSE

dependent on temperature and partial pressure of the adsorbed gas

37
Q

explain how the surface area of the adsorbent affects adsorption at solid-gas interfaces

A

the larger the surface are of the adsorbent, the more interaction and therefore, an increased rate of adsorption

the smaller the particle size of the adsorbate = larger surface area = more interaction with adsorbent

38
Q

name 7 pharmaceutical adsorbents for solid-gas interface

A

active charcoal
colloidal dioxide (aerogel)
silica gel (syloids)
diasomaceous earth (celite)
clays
aluminum hydroxide
polycarbophil

39
Q

true or false

activated charcoal is only used as an adsorbent in solid-gas interfaces

A

FALSE

also for liquid-solid

40
Q

of the 7 adsorbents mentioned, (not counting activated charcoal), which is natural and is thus preferred sometimes?

A

CLAYS

bentonite, veegum, talc, zeolites, attapulgite

41
Q

the adsorption of gases on solids is done under what conditions?

A

STP (standard temperature and pressure)

42
Q

name 5 ways in which adsorption at solid-liquid interfaces can be applied to pharmaceutics

A

-decolorizing solutions (adsorption of dye on filter)

-adsorption chromatography

-adsorption of toxins from the stomach by adsorbents (CLAYS)

-Detergency

-Wetting

43
Q

toxins can be adsorbed from the stomach by what kind of adsorbents?

A

clays

44
Q

explain how wetting works in adsorption at solid-liquid interfaces

A

the goal is to get a low contact angle (below 90 degrees) to have the maximum amount of contact

45
Q
A

Pharmaceutics II Exam 1 (9 decks)

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