Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

form and tech > powders -lecture > Flashcards

powders -lecture Flashcards

1
Q

gas state
- vancancies
- motion
characteristic properties

A

gas molecules move among vacancies

  • vigorous, chaotic, rapid motion and collide

diffusion and partial pressure are the characterisitc traits

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

liquid

  • vancancy
  • motion
  • characterisitc properties
A
  • vacancies move among molecules ( vacancies move around )

mobile molecules without orientation nor periodicity
- isotropic ( randomly distributed )

diffusion, surface tension and rheology

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

solid
movement
characteristic properties

A

well organised and immobile

molecules have orientation and periodicity ( repeating )

chracteristic properties - melting point and diffraction

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

describe the 2 mesophases between solid and liquid

and draw

A
  1. smectic - soap-like/grease-like

mobile 2d , rotate in 1 axis
orientated & arranged in equispaced planes
no periodicity within the planes

2.nematic - thread-like

mobile 3d, rotate 1 axis
orientated with no periodicity
move up and down and somewhat organised

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

what are the properties of mesophases

A

organic
elongated or rectilinear
rigid
strong dipoles and easily polarisable groups

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

2 grps of mesophases depending on the solvent

A
  1. thermotropic ( solvent-free) - temp sensi

2. lyotropic ( with solvent ) - solvent sensitive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what are the uses of mesophases

A
  • temp sensor
  • display - liquid crystals provide colours
  • stabilisation fo emulsions by inc viscosity
  • improve solubilisation of drugs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

how does mesophase improve stabilisation of emulsion

A

inc viscosity

bc there is some crystal order which can help to trap molecules and stabilise it

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

characteristics of solids

A
  • least amt of kinetic energy
  • structurally rigid to resist deformative forces,
    bc short int distance, dense and fixed
  • organised as crystalline or amorphous solids
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

main physical properties of solids

A 
physical form eg size, shape, flow 
density 
mp 
heat capacity 
porosity 
hardness 
deformability 
optical properties 
wettability 
moisture interaction 
solubility
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

liquids vs solids

  • shape
  • movement
  • traits
A

liquid

  • no set shape , takes shape of container
  • flow w relative ease
  • move freely unrestricted

for solids

  • definite mass, volume and shape
  • molecules relatively immobile and they oscillate about their mean positions
  • mechanically strong and incompressible
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

oral solid dosage forms

- multiparticulate forms

A

powders - crystals, nanoparticles, microcapsules, microspheres
granules/agglomerates
pellets spheroids, beads

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

adv of solid dosage form

A
  • better chem stability shelf life 2-3 yrs
  • dry - dosent promote microbial growth
  • lower bulk volume
  • ease of handling, convenience
  • flexible, single or multiple components
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is a

crystal form

A
  • ordered structure w arranged atoms, ions or molecules forming symmetrical and repeating patterns in 3d
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

basic repeating pattern of a crystal form is called

A

” unit cell “ of the structure

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

what is polymorphism

and why is it formed

A

ability of the solid to exist in more than one form of crystal structure - differences in crystal packing

  • different polymorphs are formed to minimise crystal lattice energy under specific thermodynamic conditions
17
Q

what varies between polymorphs and so what

A

chemically they r similar but physical properties vary
like solubility , dissolution , bioavailability , morphology , thermal etc
which is a pharmaceutical concern bc it could be unstable

18
Q

eg of 2 polymorphic forms and their examples

A

diamond - tetrahedral
atom w 4 covalent equal distanced atoms around
formed under high pressure and temp

graphite 
- hexagonal arrangement crystalline form of carbon atoms 
most stable form 
layers 
without covalnet bonds between layers 
can slide
19
Q

diff between crystalline and amorphous

A

crystalline

  • orderly arrangement
  • defined structure
  • anisotropic , sharp x ray diffraction patterns
  • sharp mp
  • definite heat of fusion
  • more chemically stable

amorphous

  • no arrangmenet
  • irregular shape
  • isotropic , no well-reoslved x-ray pattern
  • mp range
  • no definite heat of fusion
  • more liable to degradation, less chem stable
20
Q

between crystalline and amorphous which is more soluble

A

amorphous is more

crystalline’s limiting factor is solubility , so make it more amorphous to inc solubility

21
Q

difference between amorphous and nanocrystalline

A

amorphous is jsut completley disorganised

nanocrystalline is polycrystalline with a crystalline ( rganised ) site of only a new nanometers,
( areas of crystallinity and areas of non isotropic )
also has good solubility

22
Q

main methods for determining crystallinity / polymorphism

A 
( main ) xray diffractometry 
melt behaviour 
-visual - hot stage microscopy 
- differential scanning calorimetry 
raman spectrometry

others
- infrared spectroscopy
nuclear magnetic reasonance spectroscopy

23
Q

what is x ray diffraction for and how does it work

values needed

A

to determine crystallinity/ polymorphism
for determining solubiloty and thus bioavailability

  • planes of atoms in molecules give reflecting layers for
    x-rays - capture the outgoing beam and plot
  • bragg condition / braggs condition , if meets the condition then defraction occurs and outgoing beam can be plotted
    visible light - 400-800nm
    x-ray: 0.01-10nm
    ( for crystallography : powder diffraction =0.1nm)

intra-atomic spacing between planes in crystals,
typically a few angstroms’ range 1-100 angstroms 0.1-10nm

from 0-30 mins goes from crystalline to amorphous state
and once broken down , the peaks are no longer like before , orderliness of the material is destroyed

24
Q

3 results of x ray diffraction

A
  • used to check the crystal form
    (a) anhydrous carbamazepine ( beta form ) vv sharp and narrow
    (b) anhydrous carbamazepine ( alpha form ) 2 middle same 1 long
    (c) carbamazepine dihydrate 1 v long middle
25
Q

how does hot stage microscopy work

A

visual characterisation fo thermal transitions is used
may have in built sensor for calorimetric measurements also
- diff polymorphic forms have diff melting point
if orderly material then sharp mp

26
Q

how does DSC work
( differential scanning calorimetry )

include thegraph for crystalline to amorphous

A

melting point , fixed amt of heat per unit time and plot the enthalphy when it takes in or gives off heat , it will be recorded
when nothing happens - straight line

  • measure enthalphy change as a function of temp or time
    difference in the amt of heat required to inc the temp of a sample and reference

graph of crystalline to amorphous
- rmb to use only the first peak

crystalline - no melting til 246, sharp melting point
for amorphous , small transition peak
and may have another peak where the amorphous form recrystallises to the crystalline form

27
Q

what is raman scattering

A

when electromagnetic radiation is scatteredm one photon of incident radiation is annihilated and at the same time , one photon of the scattered radiation is created

if the enegry of the incident photon is equal to the scattered one, process called rayleigh scattering
if the energy is different , process is called raman scattering

28
Q

how does raman spectrometry work

eg of the graph / spectrometry result

A
  • proton activated to higher energy state but dosent return to ground , returns to higher level
  • measured as clear signals
  • raman shows the signal for crystalline and amorphous , similar plots but the peaks are sharp for crystalline and broad for amorphous
29
Q

what are the advantages of raman

A
  • distinct spectroscopic property
  • fast measurement time
  • able to measure from small spot size
    to a few microns ( measures v small sample )
30
Q

uses of raman

A

non-destructive , microscopic , chemical analysis applications
if tablet has a brown spot can use this to identify and can map out distribution of components on a surface

form and tech (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions