PHA 317 Exam 2 Interfacial Phenomena
UPDATED ACTUAL Questions and
CORRECT Answers
adsorption - CORRECT ANSWER - primarily a surface phenomenon
absorption - CORRECT ANSWER - occurs throughout th entire bulk of a substance
surface active agents, surfactants, or amphiphies - CORRECT ANSWER - molecules that
can be adsorbed and reduce surface tension.
what must be present on a molecule for it surface to have activity? - CORRECT
ANSWER - the molecule must be hydrophilic group (facing the bulk) and lipophilic group
(facing the air)
micelles - CORRECT ANSWER - clusters of molecules in the bulk of the solution. these
are formed when the surface and of liquid is fully saturated. this minimize interfacial energy
monomers - CORRECT ANSWER - individual molecules on the surface of the liquid
how can micelles solubilize lipophilic drugs? - CORRECT ANSWER - the interior of a
micelle is lipophilic (assuming molecules are in a aqueous solution), this lipophilic center can
trap lipophilic drugs and because like dissolves like the drug can solubilize
critical micellar concentration (CMC) - CORRECT ANSWER - The concentration above
which the monomers of surfactant start associating to form micelles
CMC and water properties - CORRECT ANSWER - before CMC is reached surface
properties of the liquid (surface and interfacial tension, vapor pressure) are affected. after CMC
is reached bulk properties of the liquid (density, conductivity) are affected.
, how can you use micelles to suspensions and emulsions? - CORRECT ANSWER -
lipophilic core of micelles can be used to solubilize drug molecules in solutions and suspensions.
The core can also be used to solubilize droplets of oil that is ordinarily immiscible in water.
HLB (hydrophile-lipophile balance) - CORRECT ANSWER - a measurement tool for
surface activity. The higher the HLB of an agent, the more hydrophilic it is. According to this
classification, Spans, or sorbitan esters, have low HLB values of 1.8 to 8.6, whereas Tweens, or
polyoxyethylene derivatives of spans, are hydrophilic and have high HLB values of 9.6 to 16.7.
solid-gas adsorption - CORRECT ANSWER - used in the removal of objectionable odors
from rooms or food, operation of gas masks, and measurement of dimensions of particles in a
powder.
solid-liquid adsorption - CORRECT ANSWER - used in decolorizing solutions,
adsorption chromatography, detergency, and wetting.
what affects solid-gas adsorption? - CORRECT ANSWER - the physical and chemcial
nature of the adsorbent (the material used to adsorb the gas), and the adsorbate (the substance
being adsorbed)
physical adsorption - CORRECT ANSWER - occurs due to the van der Waal's forces of
attraction, and is reversible by increasing temperature or reducing pressure. The process by
which a physically adsorbed gas is removed is called desorption.
chemical adsorption - CORRECT ANSWER - occurs due to attachment of the adsorbate to
the adsorbent by chemical bonds. Typically, only one layer (monolayer) of adsorbate is attached.
This process is irreversible
between physical and chemical adsorption, which one is reversible and which one is irreversible?
- CORRECT ANSWER - physical is reversible (by increasing temp or decreasing
pressure) and chemical is irreversible
UPDATED ACTUAL Questions and
CORRECT Answers
adsorption - CORRECT ANSWER - primarily a surface phenomenon
absorption - CORRECT ANSWER - occurs throughout th entire bulk of a substance
surface active agents, surfactants, or amphiphies - CORRECT ANSWER - molecules that
can be adsorbed and reduce surface tension.
what must be present on a molecule for it surface to have activity? - CORRECT
ANSWER - the molecule must be hydrophilic group (facing the bulk) and lipophilic group
(facing the air)
micelles - CORRECT ANSWER - clusters of molecules in the bulk of the solution. these
are formed when the surface and of liquid is fully saturated. this minimize interfacial energy
monomers - CORRECT ANSWER - individual molecules on the surface of the liquid
how can micelles solubilize lipophilic drugs? - CORRECT ANSWER - the interior of a
micelle is lipophilic (assuming molecules are in a aqueous solution), this lipophilic center can
trap lipophilic drugs and because like dissolves like the drug can solubilize
critical micellar concentration (CMC) - CORRECT ANSWER - The concentration above
which the monomers of surfactant start associating to form micelles
CMC and water properties - CORRECT ANSWER - before CMC is reached surface
properties of the liquid (surface and interfacial tension, vapor pressure) are affected. after CMC
is reached bulk properties of the liquid (density, conductivity) are affected.
, how can you use micelles to suspensions and emulsions? - CORRECT ANSWER -
lipophilic core of micelles can be used to solubilize drug molecules in solutions and suspensions.
The core can also be used to solubilize droplets of oil that is ordinarily immiscible in water.
HLB (hydrophile-lipophile balance) - CORRECT ANSWER - a measurement tool for
surface activity. The higher the HLB of an agent, the more hydrophilic it is. According to this
classification, Spans, or sorbitan esters, have low HLB values of 1.8 to 8.6, whereas Tweens, or
polyoxyethylene derivatives of spans, are hydrophilic and have high HLB values of 9.6 to 16.7.
solid-gas adsorption - CORRECT ANSWER - used in the removal of objectionable odors
from rooms or food, operation of gas masks, and measurement of dimensions of particles in a
powder.
solid-liquid adsorption - CORRECT ANSWER - used in decolorizing solutions,
adsorption chromatography, detergency, and wetting.
what affects solid-gas adsorption? - CORRECT ANSWER - the physical and chemcial
nature of the adsorbent (the material used to adsorb the gas), and the adsorbate (the substance
being adsorbed)
physical adsorption - CORRECT ANSWER - occurs due to the van der Waal's forces of
attraction, and is reversible by increasing temperature or reducing pressure. The process by
which a physically adsorbed gas is removed is called desorption.
chemical adsorption - CORRECT ANSWER - occurs due to attachment of the adsorbate to
the adsorbent by chemical bonds. Typically, only one layer (monolayer) of adsorbate is attached.
This process is irreversible
between physical and chemical adsorption, which one is reversible and which one is irreversible?
- CORRECT ANSWER - physical is reversible (by increasing temp or decreasing
pressure) and chemical is irreversible
