Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

PHA6124 LEC Manufacturing Pharmacy > Mixing > Flashcards

Mixing Flashcards

1
Q

unit operation that aims to treat two or more components, initially in an unmixed or partially mixed state

A

mixing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

done so that each unit (particle, molecule, etc.) of the components lies as nearly as possible in contact with a unit of each of the other components

A

mixing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

ideal situation when each particle lay adjacent to a particle of the other component

A

perfect mix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

probability of selecting a particular type of particle is the same at all positions and is equal to the proportion of such particles in the total mix

A

random mix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

[TRUE OR FALSE] In a perfect mix, a particular particle is the same at all positions and is equal to the proportion of such particles in the total mix

A

FALSE - random mix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Importance of Mixing

A
  1. Ensure even distribution of active components
  2. Ensure even appearance
  3. Ensure that the dosage form releases the drug at the correct site at the desired rate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Types of mixtures

A
  1. Positive
  2. Negative
  3. Neutral
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

formed from gases or miscible liquids

A

positive mixtures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

mix spontaneously and irreversibly by diffusion

A

positive mixtures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Positive mixtures mix spontaneously and irreversibly by diffusion, and tend to approach a _______________

A

perfect mix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

no energy input needed

A

positive mixtures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

materials that use this type of mixing present no problems during manufacture

A

positive mixtures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

components tend to separate out

A

negative mixtures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

continuous energy input is required to keep the components adequately dispersed

A

negative mixtures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

type of mixture that is more difficult to form and maintain

A

negative mixtures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

require a higher degree of mixing efficiency

A

negative mixtures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

static behavior

A

neutral mixtures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

components tend to mix spontaneously or segregate spontaneously once work has been input to mix them

A

neutral mixtures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

mixed powders, pastes, ointments

A

neutral mixtures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Mathematical Treatment of Mixing Process

A
  1. STD
  2. % coefficient of variation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Mechanism of mixing and demixing of powders (P-CSD)

A

convection mixing, shear mixing, and diffusion mixing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Mechanism of mixing and demixing of liquids (L-BTM)

A

bulk transport, turbulent mixing, molecular diffusion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

powder segregation

A

demixing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

transfer of relatively large group of particles from one part of the powder bed to another

A

convection mixing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
[TRUE OR FALSE] In convection mixing, transfer might occur when a mixer blade or paddle moves through the mix
TRUE
26
mainly contributes to the macroscopic mixing of powder mixtures
convection mixing
27
produce large degree of mixing fairly quickly
convection mixing
28
[TRUE OR FALSE] convection mixing occurs within the same group of particles, thus an extended mixing time is required
FALSE - does not occur in the same group of particles
29
occurs when a layer of material moves or flows over another layer
shear mixing
30
might be due to the removal of mass by convective mixing, creating an unstable shear/slip plane
shear mixing
31
cause the powder bed to collapse
unstable shear/slip plane
32
occurs in high shear mixers or tumbling mixers where the action of the mixer induces velocity gradients within the powder bed
shear mixing
33
movement of indiv particles through voids
diffusive mixing
34
voids are created by ___________
gravity
35
potential to produce random mix, resulting in a low rate of mixing
diffusive mixing
36
analogous to convective mixing of powders
bulk transport
37
movement of a relatively large amount of material from one position in the mixer to another (e.g., due to mixer paddle)
bulk transport
38
from haphazard movement of molecules when forced to move in a turbulent manner
turbulent mixing
39
in turbulent mixing, constant changes in speed and direction means that induced turbulence is _______________________ mechanism for mixing
highly effective mechanism
40
analogous to diffusive mixing in powder
molecular diffusion
41
occur with miscible fluids wherever a conc gradient exits; eventually produce well-mixed product
molecular diffusion
42
demixing; opposite effect of mixing
powder segregation
43
components tend to separate out
powder segregation
44
cause an increase in content variation in samples taken from the mix
powder segregation
45
may cause a batch to fail a uniformity of content test
powder segregation
46
particle size effects, particle density effects, particle shape effects
powder segregation
47
occurs when powder mix, owing to interactions and cohesive/adhesive forces between constituents
ordered mixing
48
most likely to occur when smaller particle exist due to their high specific surface area
Ordered Mixing
49
[TRUE OR FALSE] Smaller particles have higher specific surface area, so the attractive forces holding the particles to the adsorption site are more likely to be greater than the gravitational forces trying to separate the components
TRUE
50
ordered mixes can reduce or prevent segregation, it occurs if:
1. carrier particles vary in size 2. there is a competition for the active sites on the carrier particle 3. there are insufficient carrier particles
51
[TRUE OR FALSE] Mixers should be earthed to dissipate the static charge and the process should be carried out at a RH < approx. 40%
FALSE - >approx. 40%
52
Powder mixing equipment
1. Tumbling mixers 2. High Speed mixer-granulators 3. Fluidized bed mixers 4. Agitated mixers
53
commonly used for the mixing/blending of granules or free flowing powders but poor for cohesive or poorly flowing powders
tumbling mixers
54
common use is in blending lubricants, glidants, or external disintegrant with granules prior to tableting
tumbling mixers
55
can also be used to produce ordered mixes
tumbling mixers
56
common to use IBCs both as the mixer bowl and to either feed the hopper of a tablet or capsule machine or as the hopper itself
tumbling mixers
57
can both mix and granulate a product, removing the need to transfer the product between pieces of equipment and reducing the opportunity for segregation
high speed mixer-granulators
58
drying of granules or coating of multiparticulates
fluidized bed mixers
59
mix powders prior to granulation in the same bowl
fluidized bed mixers
60
depends on the motion of a blade or paddle through the product, and hence the main mixing mechanism is convection
agitator mixers
61
mixing is achieved by the rotation of helical blades in a hemispherical trough.
agitator mixers
62
dead spots are difficult to eliminate in this type of mixer and the shearing action caused by the movement of the blades may be insufficient to break up drug aggregates
agitator mixers
63
mixer poorly mix flowing material and is less likely to cause segregation than a tumbling mixer
agitator mixers
64
[TRUE OR FALSE] Mobile liquids with low viscosity are not easily mixed with each other
FALSE - easily mixed
65
[TRUE OR FALSE] Solid particles are readily suspended in mobile liquids, although particles settle slowly when mixing is discontinued
FALSE - settle rapidly
66
Viscous liquids are more difficult to stir and mix but they reduce the ____________________ of suspended particles
sedimentation rate
67
equipments used for the mixing of miscible liquids and susps
propeller mixer, turbine mixers, in lin mixers
68
common arrangement for medium scale fluid mixing, which may be clamped to the edge of a vessel
propeller mixers
69
[TRUE OR FALSE] Vortex forms when the centrifugal force imparted to the liquid by the propeller blades causes it to back up around the sides of the vessel and create a depression at the shaft.
TRUE
70
ratio of the diameter of a propeller stirrer to that of the vessel
1:10 - 1:20
71
propeller mixers operate at what speed
1-20 rps
72
used for more viscous fluids
turbine mixers
73
absence of an axial component, but a different head with the perforations pointing upwards can be fitted if this is desired
drawback of turbine mixers
74
as the liquids is forced through the small orifices of the diffuser rings at high velocity large shear forces are produced
turbine mixers
75
will not cope with liquids of very high viscosity, as the material will not be drawn into the mixer head
turbine mixers
76
need continuous mixing process
inline mixers
77
as an alternative to mixing fluids in batches in vessels, mobile miscible components may be fed through an inline mixer designed to create turbulence in a flowing fluid stream
inline mixers
78
mixers used in mixing semisolids
planetary mixers, sigma blade mixer
79
[TRUE OR FALSE] Semisolids will not flow easily as compared to powders and liquids
TRUE
80
Commonly found in domestic kitchen and larger machines which operate on the same principle are used in industry
planetary mixers
81
Used to mix powders, particularly if a wet mass granulation is required
planetary mixers
82
Robust mixer that will deal with stiff pastes and ointments and depends for its action on the close intermeshing of the 2 blades
sigma blade mixer
83
very difficult using primary mixers to completely disperse powder particles in a semisolid base so that they are invisible to the eye
sigma blade mixer
84
mix is usually subjected to the further action of roller mill or colloid mill, so as to rub out these particles by the intense shear generated by rollers or cones set with very small clearance between them
sigma blade mixer

PHA6124 LEC Manufacturing Pharmacy (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions