Physical Pharmacy: Intramolecular and Intermolecular Forces

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Questions and Answers

What is osmotic pressure defined as?

The pressure required to offset the movement of solvent through a semipermeable membrane (correct)

The temperature at which osmosis occurs

The pressure exerted by a pure solvent

The pressure needed to promote osmosis in a solution

Surfactants are also known as surface-active agents.

True

What phenomenon is used to describe the ability of colloidal particles to scatter light?

Faraday-Tyndall effect

The difference between the actual surface of a particle and the electroneutral region of the dispersion is known as the ______ potential.

Nernst Signup and view all the answers

Match the following types of flow with their characteristics:

Newtonian flow = Viscosity remains constant regardless of shear rate Non-Newtonian flow = Viscosity changes with shear rate Plastic flow = Requires a yield stress to start flowing Pseudoplastic flow = Decreases in viscosity with increasing shear rate Signup and view all the answers

Which method is NOT used for determining particle size?

Viscometry Signup and view all the answers

Brownian movement is the random motion of larger particles suspended in a fluid.

False Signup and view all the answers

What are the two key properties of powders important for granulation?

Fluidity and Compressibility Signup and view all the answers

What is the energy range of intermolecular forces between two polar molecules?

1-7 kcal/mole Signup and view all the answers

Cohesion refers to the attraction between different molecules.

False Signup and view all the answers

What type of intermolecular force exists between a polar and a non-polar molecule?

Dipole-induced dipole interaction Signup and view all the answers

A mixture that forms a homogenous dispersion with a particle size less than ______ is considered a true solution.

1 nm Signup and view all the answers

Match the following types of solutions with their characteristics:

True solution = Particles < 1 nm Coarse dispersion = Particles > 0.5 µm Emulsion = Liquid-liquid dispersion Suspension = Solid-liquid mixture Signup and view all the answers

Boiling point elevation occurs when a non-volatile solute is added to a volatile solvent.

True Signup and view all the answers

What happens to the vapor pressure of a solvent when a non-volatile solute is added?

It decreases Signup and view all the answers

Which of the following is NOT a colligative property of solutions?

Density change Signup and view all the answers

Study Notes

Attractive Forces in Molecules

Intramolecular Forces: Involve electron sharing; can be polar (unequal sharing creates partial charges) or non-polar (equal sharing).
Polar molecules exhibit affinity between oppositely charged particles and can involve electron transfer.
Intermolecular Forces (IMFAs):
- Energy ranges from 0.5 to 7 kcal/mole depending on interactions:
  - Polar-polar: 1-7 kcal/mole
  - Polar-nonpolar: 1-3 kcal/mole
  - Nonpolar-nonpolar: 0.5-1 kcal/mole
Cohesion vs Adhesion:
- Cohesion: attraction among similar molecules.
- Adhesion: attraction among different molecules.

States of Matter

Plasma State: Supercritical fluid state, intermediary between liquid and gas.
Liquid State:
- Dispersed systems classified into three categories based on particle size:
 - Homogenous molecular dispersion (< 1 nm).
 - Intermediate systems (1 nm – 0.5 µm).
 - Coarse dispersions (> 0.5 µm), includes emulsions and suspensions.

USP Terms of Solubility

Colligative Properties of Solutions:
- Vapor Pressure Lowering: Non-volatile solute addition reduces solvent vapor pressure based on solute concentration.
- Boiling Point Elevation: Non-volatile solutes elevate boiling point above that of pure solvent due to lowered vapor pressure.
- Freezing Point Depression: Solutions have lower freezing points compared to pure solvents.
- Osmotic Pressure: Solutions exert higher osmotic pressure than pure solvents, defined as the pressure to prevent osmosis through a semipermeable membrane.

Interfacial Phenomenon

Related to molecules at phase boundaries.
Interfacial Tension: Occurs in liquid-liquid systems.
Surface Tension: Present in solid-liquid and liquid-gas systems.
Surfactants: Also known as surface-active agents, alter surface and interfacial tensions.

Colloidal Dispersions

Properties of Colloids:
- Optical: Exhibits the Faraday-Tyndall effect, which scatters light (e.g., fog).
- Kinetic: Brownian movement, where particles appear as moving light points; diffusion balances concentration.
- Electric:
  - Nernst Potential: Potential difference between particle surfaces and surrounding neutral regions.
  - Zeta Potential: Difference in potential impacting pharmaceutical applications.

Coarse Dispersion

Stability issues present challenges in formulation.

Rheology

Viscosity (ƞ): Resistance to flow, characterized by multiple classes:
- Absolute, Kinematic, Relative viscosity distinctions.
Viscometers: Instruments used to measure viscosity.
Flow Systems:
- Newtonian Flow: Consistent viscosity regardless of shear rate.
- Non-Newtonian Flow: Viscosity varies with shear rate:
  - Shear-dependent: Plastic, Pseudoplastic, Dilatant.
  - Time-dependent: Thixotropy, Rheopexy.

Micromeritics

Particle Size Determination Methods:
- Optical Microscopy, Sieve Analysis, Sedimentation Method, Automatic Particle Counters (Coulter, HIAC/Royco, Gelman).
Particle Volume: Total space occupied by powder calculated as Vb = Vp + intra + inter-spaces.
Particle Density: Measure of mass per unit volume.
Porosity (ϵ): Total voids/spaces in particles.
Properties for Granulation:
- Fluidity: Ability of powder to flow.
- Compressibility: Capacity to reduce volume under pressure.

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Description

Explore the concepts of attractive forces in molecules, including intramolecular and intermolecular forces. This quiz covers key definitions, examples, and energy considerations related to polar and non-polar interactions. Test your understanding of these fundamental chemical principles.