Week 3

Question 1

Coarse and colloidal disperse systems are [Select all that apply]

• non-homogeneous
• homogeneous
• made of dispersed molecules
• made from dispersed particle

Answer 1

non-homogeneous

made from dispersed particle

Question 2

Match the type of non-homogeneous disperse system to its composition:
-Suspension
-Emulsion
-Aerosol
Options:
-an immiscible liquid dispersed in a liquid
-an immiscible solid dispersed in a liquid
-an immiscible solid/liquid dispersed in air

Answer 2

suspension : an immiscible solid dispersed in a liquid

emulsion: an immiscible liquid dispersed in a liquid
aerosol: an immiscible solid/liquid dispersed in air

Question 3

The force causing interfacial or surface tension is due to?

Answer 3

immiscibility of the two surfaces causing molecules on the surface/ interface to pull inward

Question 4

Interfacial tension occurs between any _________, while surface tension occurs between _______

Answer 4

two surfaces except for air

any surface and air

Question 5

The kinetic properties that affect a two phase non-homogeneous system are

Answer 5

gravity and Brownian motion

Question 6

Brownian motion _____ a disperse system stability by causing particles to move __________ in the dispersion medium

Answer 6

decreases

in all directions

Question 7

Gravity _____ a disperse system stability by causing particles to move ______ in the dispersion medium.

Answer 7

decreases

up or down

Question 8

Based on the Stokes equation, what happens to the settling rate when the viscosity of the dispersed system increases?

• increases
• decreases
• remains the same

Answer 8

decreases

Question 9

Based on the Stokes equation, what happens to the settling rate when the particle size of the dispersant decreases?

• increases
• decreases
• remains the same

Answer 9

decreases

Question 10

Based on the Einstein equation, what happens to the rate of Brownian motion when the particle size of the dispersant increases?

• increases
• decreases
• remains the same

Answer 10

decreases

Question 11

Based on the Einstein equation, what happens to the Brownian motion displacement when the dispersant’s particle size increases?

• increases
• decreases
• remains the same

Answer 11

decreases

Question 12

The electric property that effects a two phase non-homogeneous system is?

Answer 12

zeta potential

Question 13

Zeta potential values of 50 mV indicate _________ between the particles, while 0 mV zeta potential values indicate ____________ between the particles.

Answer 13

high repulsive forces

high attractive forces

Question 14

Particles that have very high repulsive forces will:
form loose sediments that do disperse
form strong sediments that do disperse
form strong sediments that do not re-disperse
form loose sediments that do not re-disperse

Answer 14

form strong sediments that do not re-disperse

Question 15

Particles which have no repulsive forces, very high attractive forces, and 0 mV zeta potential will:
form loose sediments that do disperse
form strong sediments that do disperse
form strong sediments that do not re-disperse
form loose sediments that do not re-disperse

Answer 15

form strong sediments that do not re-disperse

Question 16

Particles which have optimized or adjusted zeta potential will:
form loose sediments that do disperse
form strong sediments that do disperse
form strong sediments that do not re-disperse
form loose sediments that do not re-disperse

Answer 16

form loose sediments that do disperse

Question 17

Optimizing the zeta potential means adjusting the zeta potential to have:
low attractive forces to form flocs 
high attractive forces to form flocs 
high repulsive forces to form flocs 
no attractive forces to form flocs

Answer 17

low attractive forces to form flocs

Question 18

Examples of irreversible phase separation in non-homogeneous two-phase dispersions include:
Caking and cracking 
Caking and creaming 
Floc formation and cracking 
Floc formation and creaming

Answer 18

Caking and cracking

Question 19

Reducing which of the following will improve the stability of non-homogeneous 2 –phase disperse systems? Select all that apply.

• Interfacial tension
• Particle aggregation
• Particle deaggregation
• Floc formation

Answer 19

Interfacial tension

Particle aggregation

Question 20

Match the colloid type with its stabilization mechanism in non-homogeneous two-phase dispersions.
Soluble colloids
Association colloids
Particulate colloids
options:
Steric and/or Electrostatic stabilization
Steric stabilization
Electrostatic stabilization

Answer 20

Soluble colloids: Steric stabilization
Association colloids: Steric and/or Electrostatic stabilization
Particulate colloids: Electrostatic stabilization

Question 21

Which of the following colloid(s) enhance stability without affecting the viscosity of the dispersion medium?
Soluble colloids
Association colloids
Particulate colloids

Answer 21

Association colloids

Question 22

Zwitterionic surfactants or association colloids exhibit?
negative charges 
positive charges 
both negative and positive charges 
neither negative nor positive charges

Answer 22

both negative and positive charges

Question 23

HLB is the system of rating surfactants in terms of their ________ which helps identify their function in various disperse systems.

Answer 23

hydrophilicity and lipophilicity

Question 24

Viscosity is defined as the rate of?

Answer 24

flow of fluids

Question 25

Viscosity of Newtonian fluids: changes with changes in shear rate changes with changes in shear stress does not change with changes in shear rate cannot be predicted based on shear stress

Answer 25

does not change with changes in shear rate

Question 26

The viscosity of pseudoplastic fluids: decreases with a reduction in shear rate increases with a reduction in shear rate decreases with an increase in shear rate increases with an increase in shear rate

Answer 26

decreases with an increase in shear rate

Question 27

``` Which type of rheology is usually avoided in the pharmaceutical setting? Newtonian Plastic Thixotropic Dilatant ```

Answer 27

Dilatant

Question 28

``` Components of an emulsion include an _____ dispersed in an ______ using an _______ options: internal phase emulsifier external phase ```

Answer 28

internal phase, external phase, emulsifier

Question 29

``` Emulsions typically contain? two immiscible solids a liquid in an immiscible solid two immiscible liquid a solid in an immiscible liquid ```

Answer 29

two immiscible liquid

Question 30

``` Emulsions can be characterized based on. [Select all that apply] their phases the size of the dispersed particles the viscosity of the external phase the type of emulsifier used ```

Answer 30

their phases | the size of the dispersed particles

Question 31

The external phase in an O/W emulsion is? oil water wetting agent

Answer 31

water

Question 32

Colloidal emulsions have dispersed phase sizes that are?

Answer 32

10-200 nm

Question 33

The dominant force in coarse emulsions is ___________ due to the size of the _____________.

Answer 33

gravity; dispersed particle

Question 34

Microemulsions tend to have higher/lower stability due to higher/lower surfactant concentration.

Answer 34

higher; higher

Question 35

T/F Emulsions can sometimes be used to deliver only in the internal phase

Answer 35

true

Question 36

T/F Emulsions can carry high drug concentrations

Answer 36

false

Question 37

A lipophilic drug delivered in an emulsion requires an ___ as the internal phase of the formulation

Answer 37

oil

Question 38

A surfactant with an HLB of _____________ is needed to prepare an O/W emulsion.

Answer 38

8-19

Question 39

Which type of colloids must be used in an emulsion to stabilize the interface and reduce interfacial tension? soluble colloids association colloids particulate colloids

Answer 39

association colloids

Question 40

``` Which type of excipient will promote flocculation in emulsions? Preservative Antioxidant Particulate hydrocolloid Tonicity agent ```

Answer 40

Particulate hydrocolloid

Question 41

``` Reversible physical stability issues with emulsions include___________. [Select all that apply] flocculation cracking creaming coalescence ```

Answer 41

flocculation and creaming

Question 42

Oxidation in emulsions is commonly associated with?

Answer 42

oil

Question 43

T/F All coarse emulsions can be administered parenterally by the IV route.

Answer 43

false

Question 44

``` A major concern with microemulsion use parenterally is ___________. options: low stability due to gravity high surfactant concentration risk of pulmonary embolisms risk of microbial contamination ```

Answer 44

high surfactant concentration

Question 45

Drug E is available as a W/O emulsion. Drug E has a MW of 310 Da and a log Ko/w of 0.5. What will be the rate limiting step for Drug E in this dosage form? Diffusion coefficient Both diffusion coefficient & partition coefficient Partition coefficient Neither diffusion coefficient & partition coefficient

Answer 45

Partition coefficient