Properties of Solids I

States of Matter

• Solids, liquids, and gases are the three states of matter.
• The different states of matter are due to differences in intermolecular forces.
• Substances that exist as solids at room temperature have stronger intermolecular forces compared to liquids and gases.
• Energy can be transferred into kinetic (thermal) energy which increases temperature.
• Gases are compressible, liquids are not, and solids are not.
• Temperature increases the kinetic energy of molecules, increasing the movement of particles, thus causing phase transformations.
• Pressure can also cause phase transformations in a closed system, with increased pressure favoring the liquid and solid states.

Pharmaceutical Gases

• Pharmaceutical gases include Nitrous oxide, nitric oxide, oxygen, and carbon dioxide.
• Aerosols often use liquefied gases as a dispersion medium or propellant.

Solids

• Solids can be crystalline or amorphous.
• Crystalline solids have a repeating molecular arrangement, like polymorphs.
• Amorphous solids lack a long-range repeating order.
• Pharmaceutical salts are formed from acidic or basic drugs with a counterion to form a crystalline salt.
• Cocrystals are crystalline molecular complexes formed from two or more neutral molecules.
• When designing pharmaceuticals, it is important to consider the solid form as it affects solubility, dissolution rate, bioavailability, hygroscopicity, manufacturing properties, and stability.

Solid Stability

• Temperature influences solid stability, causing transformations like dehydration and melting.
• The melting point of solids relates to the magnitude of intermolecular forces.
• The heat of fusion is the energy required to transform a solid into a liquid.

Powders

• Powder is a physical form of a substance composed of finely divided particles.
• Powders can be classified as very coarse, coarse, moderately coarse, fine, and very fine based on their particle size.
• The particle size, size distribution, and shape of powders are important micromeritic properties influencing mixing, blending, dose uniformity, powder flow, aerosolization, dissolution, and suspendability characteristics.

Particle Size Analysis

• Sieving is one method for particle-size analysis.
• Optical microscopy, scanning electron microscopy, and transmission electron microscopy are common techniques to determine particle size.

Micromeritic Properties

• Micromeritics studies the properties of powders involving: particle size, shape, angle of repose, true density, bulk density, porosity, voids, true volume, bulk volume, and bulkiness.
• True volume is the space occupied by particles themselves and is determined by true density.
• Bulk volume is the total volume of the powder including the spaces between particles.
• Void is the ratio of space over the bulk volume.
• Porosity is a percentage calculated from the void.
• Bulkiness is the reciprocal of apparent density.
• The angle of repose describes how easily a powder flows.

Wettability of Powders

• Wettability is the ability of a liquid to spread across a solid surface.
• The contact angle is a measure of wettability.
• Young's equation describes the relationship between surface tensions and contact angle.
• Wettability affects the dispersion of powders in liquids, the penetration of liquids into tablets, and the hardness of tablets.

Explore the fundamental concepts of states of matter, including solids, liquids, and gases, and their molecular behavior. This quiz also covers the role of pharmaceutical gases and their applications in various fields. Test your understanding of intermolecular forces, phase transformations, and the unique properties of different states.