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Clare's lectures semester 2 > Principles of the solid state > Flashcards

Principles of the solid state Flashcards

1
Q

Solids are highly ordered packing. TRUE OR FALSE?

A

TRUE

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2
Q

Gases and liquid have no packing order. TRUE OR FALSE?

A

TRUE

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3
Q

Name some of the physicichemical properties that impact the solid state?

A
  • Solubility
  • Dissolution rate
  • Melting point
  • Bioavailability
  • Surface activity
  • Density
  • Stability
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4
Q

What two states can a solid be in?

A
  • Amorphous

- Crystalline

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5
Q

Name the different types of crystalline?

A
  • Polymorphs
  • Co-crystals
  • Solvates, Hydrates
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6
Q

Describe the properties of the crystalline state

A
  • Molecules are arranged in orderly defined manner with same repeating units
  • Lower potential energy than amorphous state
  • Repeating units can be arranged differently within the crystalline form of the same substance
  • Different crystalline forms of the same substance posses different melting points/temp at which ordered lattice breaks down)
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7
Q

What are the methods for crystallisation?

A
  • Supersaturated solution
  • Crystallisation through cooling molten sample below its melting point
  • Precipitation of solids in solutions
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8
Q

Provide examples for Crystallisation through cooling molten sample below its melting point

A
  • Suppositories
  • Creams
  • Gels
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9
Q

Provide examples for precipitation of solids in solutions

A
  • Evaporation
  • Addition of anti-solvent
  • After solubility of samples changed by temp/pressure/ph of the system
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10
Q

Name and describe the different steps involved in the crystallisation process?

A

-Nucleation : First step of forming crystals
/a small mass (solute molecules) cluster together to form a nuclei on which a crystal can grow
-Growth : The continued growth of the nuclei

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11
Q

In order to achieve nuleation and growth the solution must not be supersaturated. TRUE OR FALSE?

A

FALSE

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12
Q

What is polymorphism?

A
  • When a crystalline state solid possesses
  • different crystalline forms
  • Different packing pattern
  • Different lattice energies
  • Different properties
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13
Q

Polymorphism can present in a stable and metastable form. TRUE OR FALSE?

A

TRUE

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14
Q

Describe both stable and metastable form of polymorphism

A

Stable form - Higher MP, slower dissolution rate

Metastable form - Lower MP, faster dissolution, increase in apparent solubility

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15
Q

Metastable form will transform into most stable form. TRUE OR FALSE?

A

TRUE

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16
Q

What is monotropic polymorphism?

A

-Only one stable polymorphic form (metastable will transform into stable over time)

17
Q

What is enantropic polymorphism?

A

-Material reversibly transformed between alternative stable forms.

18
Q

Which one is less common, monotropic or enantropic polymorphism?

A

Enantropic

19
Q

During crystallisation the solvent molecules can be trapped in the crystal lattice. TRUE OR FALSE?

A

TRUE

20
Q

What is monohydride and dihydride?

A
  • Monohydride: 1 molecule of water:Molecule substance

- Dihydride: 2 molecules of water: 1 Molecule substance

21
Q

What is a solvate?

A

-Another solvent instead of water e.g organic solvents such as ethanol

22
Q

What is pseudopolymorphism?

A

-Used to describe the different between hydrates and anhydrous forms

23
Q

The hydrate form can have a slower or faster dissolution. TRUE OR FALSE?

A

TRUE

24
Q

Describe the properties of amorphous state?

A
  • lower packing efficiency (less ordered)
  • Greater intemolecular distance
  • Greater molecular mobility
  • Greater potential energy
  • Often higher solubility
25
Q

Why are solids amorphous?

A
  • Insufficient solidification time for molecules to form order
  • Lack of kinetic energy to overcome barrier between crystal-liquid interface
  • The crystalline process has been broken through processing
26
Q

Low MW materials are commonly amorphous. TRUE OR FALSE?

A

TRUE

27
Q

Larger MW compounds such as polymers disordered exhibit both ordered and disordered region - semi crystalline. TRUE OR FALSE?

A

TRUE

28
Q

Degree of crystallinity results in different properties. TRUE OR FALSE?

A

TRUE

29
Q

Amorphous forms have a characteristic temp at which there is a major change in properties, known as the GLASS TRANSITION TEMPEARTURE (Tg). TRUE OR FALSE?

A

TRUE

30
Q

What occurs when Tg is greater?

A
  • Glassy brittle state

- Lower mobility of molecules

31
Q

What occurs when Tg is less than?

A
  • Rubbery

- Higher mobility of molecules

32
Q

What are plasticisers and provide an example of a good plasticiser?

A
  • Substances added to reduce Tg of an amorphous material

e. g Water

33
Q

At relatively high humdity’s amorphous materials do not absorb water. TRUE OR FALSE?

A

FALSE

34
Q

Plasticising material with water leads to the reverting to the crystalline state leading to weight loss. TRUE OR FALSE?

A

TRUE

35
Q

What is crystal habit?

A
  • Eternal shape of the crystal due to rate of crystal gowth at different faces influenced by crystalline conditions.
36
Q

Crystal habit can be different for different internal packing but also different for the same packing. TRUE OR FALSE?

A

TRUE

37
Q

Crystal habit affects drug properties, such as dissolution rate, powder flow and stability. TRUE OR FALSE?

A

TRUE

Clare's lectures semester 2 (10 decks)

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