Properties of Solids II

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Questions and Answers

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?

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?

Viscosity and temperature

Melting point and solubility

Diffusion coefficient and molecular size (correct)

Heat capacity and thermal conductivity

What is pseudopolymorphism?

A form of polymorphism where different solvents create different crystalline structures Signup and view all the answers

What is the relationship between purity and melting point in a compound?

As purity increases, the melting point becomes narrower and higher Signup and view all the answers

Equivalent sphere diameter is based on which property?

All of the above Signup and view all the answers

What form of polymorphism exists when one polymorph is stable under certain conditions, while another is stable under different conditions?

Enantiotropy Signup and view all the answers

Which of the following techniques is suitable for analyzing particles larger than 1 µm in size?

Optical Microscopy Signup and view all the answers

Which technique is most effective for analyzing the interaction of light with a material's crystal structure?

Optical Microscopy Signup and view all the answers

What happens to the melting point of a substance as its purity increases?

It becomes narrower and higher. Signup and view all the answers

Which statement correctly describes eutectification?

It refers to the lowest melting point composition of two compounds. Signup and view all the answers

Which property is characterized by the ability of a material to exist in more than one crystal structure?

Polymorphism Signup and view all the answers

What technique is best suited for observing smaller particles in solids or dried films?

Scanning Electron Microscopy Signup and view all the answers

How does particle size generally affect the speed of dissolution in a liquid?

Smaller particles dissolve faster. Signup and view all the answers

What effect does porosity have on bulk density?

Porosity decreases bulk density. Signup and view all the answers

Which analysis method primarily evaluates the thermal stability of materials?

Differential Scanning Calorimetry (DSC) Signup and view all the answers

What is the primary purpose of Fourier Transform Infrared (FTIR) Spectroscopy in material analysis?

To identify crystal forms. Signup and view all the answers

Which factor typically influences gas behavior when transitioning to liquids or solids?

Both temperature and pressure Signup and view all the answers

What is the eutectic point characterized by in a binary eutectic phase diagram?

The point where the mixture of two compounds has the lowest melting point. Signup and view all the answers

How does the presence of impurities affect the melting point of a compound?

The melting point increases and becomes broader. Signup and view all the answers

What effect does particle size have on the dissolution rate of a drug?

Smaller particles dissolve faster. Signup and view all the answers

What is a key characteristic of enantiotrophs in polymorphism?

One form is stable over a certain temperature and pressure range, while the other is stable under different conditions. Signup and view all the answers

Which of the following statements is true regarding metastable polymorphs?

They convert to more stable forms over time or under specific conditions. Signup and view all the answers

What does polymorphism refer to in materials science?

Ability to exist in more than one crystal structure. Signup and view all the answers

In the context of polymorphism, what are solvates?

Solids with solvent molecules incorporated into their crystal lattice. Signup and view all the answers

What is the melting point phenomenon called when the melting point of a mixture is lower than the melting points of the individual components?

Melting Point Depression Signup and view all the answers

What does porosity represent in powder characterization?

Percent of void within the total bulk volume. Signup and view all the answers

What is the primary purpose of using sieves in particle size analysis?

To separate particles by size. Signup and view all the answers

How does increasing the surface tension of a liquid affect its wettability?

Reduces wettability. Signup and view all the answers

What defines a eutectic point in a phase diagram?

The temperature and composition where the mixture fully transitions from solid to liquid. Signup and view all the answers

Why is smaller particle size usually associated with worse powder flow?

Due to greater surface area. Signup and view all the answers

If the mass of a powder is 10 g and its bulk volume is 50 mL, what is its bulk density?

0.5 g/mL Signup and view all the answers

What is the void fraction of a powder with a bulk volume of 20 mL and a true volume of 5 mL?

0.80 Signup and view all the answers

What happens to diffusion when the temperature increases?

Diffusion increases Signup and view all the answers

What is the bulkiness of a powder with a bulk density of 0.30 g/mL?

2.0 mL/g Signup and view all the answers

How is bulk density calculated?

Mass / Bulk Volume Signup and view all the answers

What is the primary function of polymorphism screening in pharmaceutical research?

To identify different crystal forms that could impact drug performance Signup and view all the answers

What happens to the bulk density if the bulk volume increases while the mass remains the same?

Bulk density decreases Signup and view all the answers

Which factor does not affect polymorphism?

Atomic mass of elements in the compound Signup and view all the answers

What does the term ‘bulkiness’ of a powder refer to?

The ratio of bulk volume to mass Signup and view all the answers

Which thermal analysis technique measures changes in sample mass due to decomposition or vaporization?

Thermogravimetric Analysis (TGA) Signup and view all the answers

What happens to a solid's wettability when surface tension of the solid-liquid interface decreases?

Wettability improves Signup and view all the answers

What does Differential Scanning Calorimetry (DSC) primarily measure?

Heat flow differences between a sample and reference Signup and view all the answers

Which equation describes the relationship between molecular size, solvent viscosity, and diffusion coefficient?

Stokes-Einstein Equation Signup and view all the answers

Which technique is used to measure changes in a sample’s dimension as a function of temperature?

Thermomechanical Analysis (TMA) Signup and view all the answers

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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Description

This quiz covers essential concepts related to powder properties, including bulkiness, porosity, and particle size, as well as the important topic of polymorphism in materials. Understand how these factors impact the behavior and applications of powders in various industries. Test your knowledge and see how well you grasp these fundamental principles.