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Questions and Answers
What does a high bulkiness value indicate about a powder?
What does a high bulkiness value indicate about a powder?
- High volume per unit mass (correct)
- Low porosity
- High density
- Small particle size
What is the main reason for the broader melting point range in impure substances?
What is the main reason for the broader melting point range in impure substances?
- Increased intermolecular forces
- Stronger covalent bonds
- Decreased energy needed to disrupt the crystal lattice (correct)
- Higher heat capacity
What does the Stokes-Einstein Equation relate to in terms of physical properties?
What does the Stokes-Einstein Equation relate to in terms of physical properties?
- Viscosity and temperature
- Melting point and solubility
- Diffusion coefficient and molecular size (correct)
- Heat capacity and thermal conductivity
What is pseudopolymorphism?
What is pseudopolymorphism?
What is the relationship between purity and melting point in a compound?
What is the relationship between purity and melting point in a compound?
Equivalent sphere diameter is based on which property?
Equivalent sphere diameter is based on which property?
What form of polymorphism exists when one polymorph is stable under certain conditions, while another is stable under different conditions?
What form of polymorphism exists when one polymorph is stable under certain conditions, while another is stable under different conditions?
Which of the following techniques is suitable for analyzing particles larger than 1 µm in size?
Which of the following techniques is suitable for analyzing particles larger than 1 µm in size?
Which technique is most effective for analyzing the interaction of light with a material's crystal structure?
Which technique is most effective for analyzing the interaction of light with a material's crystal structure?
What happens to the melting point of a substance as its purity increases?
What happens to the melting point of a substance as its purity increases?
Which statement correctly describes eutectification?
Which statement correctly describes eutectification?
Which property is characterized by the ability of a material to exist in more than one crystal structure?
Which property is characterized by the ability of a material to exist in more than one crystal structure?
What technique is best suited for observing smaller particles in solids or dried films?
What technique is best suited for observing smaller particles in solids or dried films?
How does particle size generally affect the speed of dissolution in a liquid?
How does particle size generally affect the speed of dissolution in a liquid?
What effect does porosity have on bulk density?
What effect does porosity have on bulk density?
Which analysis method primarily evaluates the thermal stability of materials?
Which analysis method primarily evaluates the thermal stability of materials?
What is the primary purpose of Fourier Transform Infrared (FTIR) Spectroscopy in material analysis?
What is the primary purpose of Fourier Transform Infrared (FTIR) Spectroscopy in material analysis?
Which factor typically influences gas behavior when transitioning to liquids or solids?
Which factor typically influences gas behavior when transitioning to liquids or solids?
What is the eutectic point characterized by in a binary eutectic phase diagram?
What is the eutectic point characterized by in a binary eutectic phase diagram?
How does the presence of impurities affect the melting point of a compound?
How does the presence of impurities affect the melting point of a compound?
What effect does particle size have on the dissolution rate of a drug?
What effect does particle size have on the dissolution rate of a drug?
What is a key characteristic of enantiotrophs in polymorphism?
What is a key characteristic of enantiotrophs in polymorphism?
Which of the following statements is true regarding metastable polymorphs?
Which of the following statements is true regarding metastable polymorphs?
What does polymorphism refer to in materials science?
What does polymorphism refer to in materials science?
In the context of polymorphism, what are solvates?
In the context of polymorphism, what are solvates?
What is the melting point phenomenon called when the melting point of a mixture is lower than the melting points of the individual components?
What is the melting point phenomenon called when the melting point of a mixture is lower than the melting points of the individual components?
What does porosity represent in powder characterization?
What does porosity represent in powder characterization?
What is the primary purpose of using sieves in particle size analysis?
What is the primary purpose of using sieves in particle size analysis?
How does increasing the surface tension of a liquid affect its wettability?
How does increasing the surface tension of a liquid affect its wettability?
What defines a eutectic point in a phase diagram?
What defines a eutectic point in a phase diagram?
Why is smaller particle size usually associated with worse powder flow?
Why is smaller particle size usually associated with worse powder flow?
If the mass of a powder is 10 g and its bulk volume is 50 mL, what is its bulk density?
If the mass of a powder is 10 g and its bulk volume is 50 mL, what is its bulk density?
What is the void fraction of a powder with a bulk volume of 20 mL and a true volume of 5 mL?
What is the void fraction of a powder with a bulk volume of 20 mL and a true volume of 5 mL?
What happens to diffusion when the temperature increases?
What happens to diffusion when the temperature increases?
What is the bulkiness of a powder with a bulk density of 0.30 g/mL?
What is the bulkiness of a powder with a bulk density of 0.30 g/mL?
How is bulk density calculated?
How is bulk density calculated?
What is the primary function of polymorphism screening in pharmaceutical research?
What is the primary function of polymorphism screening in pharmaceutical research?
What happens to the bulk density if the bulk volume increases while the mass remains the same?
What happens to the bulk density if the bulk volume increases while the mass remains the same?
Which factor does not affect polymorphism?
Which factor does not affect polymorphism?
What does the term ‘bulkiness’ of a powder refer to?
What does the term ‘bulkiness’ of a powder refer to?
Which thermal analysis technique measures changes in sample mass due to decomposition or vaporization?
Which thermal analysis technique measures changes in sample mass due to decomposition or vaporization?
What happens to a solid's wettability when surface tension of the solid-liquid interface decreases?
What happens to a solid's wettability when surface tension of the solid-liquid interface decreases?
What does Differential Scanning Calorimetry (DSC) primarily measure?
What does Differential Scanning Calorimetry (DSC) primarily measure?
Which equation describes the relationship between molecular size, solvent viscosity, and diffusion coefficient?
Which equation describes the relationship between molecular size, solvent viscosity, and diffusion coefficient?
Which technique is used to measure changes in a sample’s dimension as a function of temperature?
Which technique is used to measure changes in a sample’s dimension as a function of temperature?
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Study Notes
Powder Properties
- Bulkiness: A higher bulkiness value indicates a higher volume per unit mass.
- Porosity: Refers to the void space within the powder’s total bulk volume.
- Bulk Density: Calculated by dividing the mass by the bulk volume.
- True Volume: The volume occupied by the solid particles only.
- Void Fraction: The ratio of empty space in the bulk volume to the total volume.
- Particle Size: Smaller particles generally lead to worse powder flow due to increased surface area.
Polymorphism
- Polymorphism: The ability of a material to exist in more than one crystalline structure.
- Enantiotropy: A form of polymorphism where one polymorph is stable under certain conditions, while another is stable under different conditions.
- Monotropy: Only one polymorph is stable below the melting point.
- Pseudopolymorphism: Different solvents produce different crystalline structures.
- Solvates: Solids with solvent molecules incorporated into their crystal lattice.
- Metastable polymorphs: Less stable forms that convert to more stable forms over time or under specific conditions.
- Eutectic Point: The point in a binary eutectic phase diagram where the mixture of two compounds has the lowest melting point.
Melting Point
- The melting point of a substance is the temperature at which it transitions from a solid to a liquid.
- Impurities: Impurities in a substance lead to a broader melting point range due to a decreased energy required to disrupt the crystal lattice.
- Purity: Increased purity results in a narrower and higher melting point.
Dissolution
- Particle size: Smaller particle size increases the dissolution rate of a drug.
Wettability
- Young’s equation: Describes the balance of surface tension forces at the solid-liquid interface.
- Surface Tension: A lower surface tension at the solid-liquid interface leads to improved wettability.
Techniques for Analysis
- Differential Scanning Calorimetry (DSC): Measures heat flow differences between a sample and a reference.
- Thermogravimetric Analysis (TGA): Measures changes in sample mass due to decomposition or vaporization.
- Thermomechanical Analysis (TMA): Measures changes in a sample’s dimension as a function of temperature.
- Optical Microscopy: Suitable for analyzing particles larger than 1 µm.
- Scanning Electron Microscopy: Used for observing smaller particles on dried films.
- Fourier Transform Infrared (FTIR) Spectroscopy: Used to obtain an infrared spectrum for polymorph identification.
Other Key Concepts
- Diffusion: The movement of molecules from a region of higher concentration to lower concentration.
- Diffusion Coefficient: Related to molecular size, solvent viscosity, and temperature by the Stokes-Einstein equation.
- Kinetic Energy: Increases as temperature increases.
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