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SOLID STATELEC 1
By Dr Manal AL Soub
STATES OF MATTER SOLIDS
•Particles of solids are tightly packed, vibrating about a fixed position.
•Solids have a definite shape and a definite volume.
STATES OF MATTERLIQUID
Particles of liquids are tightly packed, but are far enough apart to slide over one another.
Liquids have an indefinite shape and a definite volume.
STATES OF MATTERGAS
Particles of gases are very far apart and move freely.
Gases have an indefinite shape and an indefinite volume.
Solidrefers to the state of matter in which the particles are
locked into place without much freedom of movement. They can be locked into crystal lattices or just kind of stuck together with intermolecular forces so tightly that they can’t really move around.
Solids differ from liquids in that the particles in liquids, while still stuck together, do have some freedom of motion.
Solids differ from gases in that gas molecules really don’t interact with each other much, flying all over the place
PHASE CHANGESDescription of Phase Change
Term for Phase Change
Heat Movement DuringPhase Change
Solid to liquid
MeltingHeat goes into the solid as it melts.
Liquid to solid Freezing
Heat leaves the liquid as it freezes.
PHASE CHANGESDescription
of Phase Change
Term for Phase Change
Heat Movement During
Phase Change
Liquid to gas
Vaporization, which includes boiling and evaporation
Heat goes into the liquid as it vaporizes.
Gas to liquid Condensation Heat leaves the gas as it condenses.
Solid to gas Sublimation Heat goes into the solid as it sublimates.
STATES OF MATTER
SOLID LIQUID GAS
Tightly packed, in a regular pattern
Vibrate, but do not move from place to
place
Close together with no regular
arrangement.Vibrate, move
about, and slide past each other
Well separated with no regular
arrangement.Vibrate and move
freely at high speeds
10
What is solid…..to pharmacy?
Majority of drugs and excipients exist as solidsVarious dosage forms are prepared
e.g. tablets, emulsions
11
Classification of Solids• Amorphous
• Crystalline
– Polymorphism
– Solvate and hydrates
–Co-crystal
12
Crystalline Solids• E.g. diamond, graphite
• Regular shape i.e. fixed geometric patterns
• Incompressible
• Definite /specific boiling points
• Diffract X-rays
13
Crystal Structure
• Crystals contain highly ordered molecules or atoms held together by non-covalent interactions
• E.g. NaCl has the cubic structure
14
Can be defined on the basis of variations on the themes of 7 systems
Types of Crystal Structure
1. Cubic- sodium chloride
2. Tetragonal- urea
3. Hexagonal - iodoform
4. Rhombic- iodine
5. Monoclinic- sucrose
6. Triclinic- boric acid
7. Trigonal
15
Angles & lengths that describe crystal habit α = between length & breadthβ = between breadth & heightγ = between length & height
Crystal Angle of axes Length of axes Examples
Cubic (regular) α = β = γ = 90º x =y =z NaCl
Tetragonal α = β = γ = 90º x =y ≠z NiSO4
Orthorhombic α = β = γ = 90º x ≠y ≠z K2MNO4
Monoclinic α = β = γ ≠ 90º x ≠y ≠z Sucrose
Triclinic (asymmetric) α ≠β ≠ γ ≠ 90º x ≠y ≠z CuSO4
Trigonal (rhombohedral) α = β = γ ≠90º x =y =z NaNO3
Hexagonal Z at 90º to base - AgNO3
17
Monoclinic
simple monoclinic
centered monoclinic
18
Tetragonal
simple tetragonal body-centeredtetragonal
19
Orthorhombic xtals
simple orthorhombic
base-centeredorthorhombic
body-centeredorthorhombic
face-centeredorthorhombic
20
Bravais Lattices1. End-centred
i. Monoclinic
ii. orthorombic
2. Face-centredi. Cubic (NaCl)
ii. Orthorombic
3. Body-centredi. Cubic tetragonal
ii. Orthorombic
Total of 14 possible types of unit cells
For drugs, only 3 types:
1. Triclinic
2. Monoclinic
3. Orthorombic
21
FCC Structure of NaCl• Small spheres
represent Na+ ions, large spheres represent Cl- ions.• Each sodium ion is
octahedrally surrounded by six chloride ions and vice versa.
22
CrystallisationCrystallisation steps from solution:-
1. Supersaturation of the solutione.g. cooling, evaporation, addition of precipitant or chemical reaction
2. Formation of crystal nucleie.g. collision of molecules, deliberate seeding
3. Crystal growth around the nuclei
23
Crystal GrowthSteps involved:1. Transport of molecules to the surface2. Arrangement in the lattice
Degree of agitation in the system affects the diffusion coefficient, thus affects crystal growth.
24
Precipitation
1. Induced by altering pH of solution to reach saturation solubility.
2. By chemical reaction to produce precipitate from a homogeneous solution.
The rate of reaction is important in determining habit.
25
Crystallization from Supersaturated Solutions of Sodium Acetate
• Description: A supersaturated solution of sodium acetate is crystallized by pouring it onto a seed crystal, forming a stalagmite-like solid. Heat is radiated from the solid.
26
Polymorphisms
• When compounds crystallise as different polymorphs, properties change.
• Molecules arrange in two or more ways in the crystal: packed differently in crystal lattice, different orientation, different in conformation of molecules at lattice site.
• X-ray diffraction patterns change.
27
Polymorphism of Spironolactone• A diuretic (no potassium loss)• 2 polymorphic forms and 4 solvated crystalline• Form 1: spironolactone powder is dissolved in
acetone at a temperature near boiling point and cooled to 0 deg. C within a few hours – needle-like
• Form 2: powder dissolved in acetone or dioxane or chloroform and acetone allowed to evaporate for several weeks – prism
28 PHM1213 Physical Pharmacy 1 2008/9
Polymorphs of spironolactone
1
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Amorphous Solids• E.g. silica gel, synthetic plastics/polymers• Irregular shape
- molecules are arranged in a random manner• No definite melting point
- no crystal lattice to break• Exhibit characteristic glass transition temperature, Tg• Flow when subject to pressure over time• Isotropic i.e. same properties in all direction• Affect therapeutic activity e.g. amorphous antibiotic
novobiocin is readily absorbed and therapeutically active compared to the crystalline form
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