Questions and Answer Keys : Physical Pharmacy II Unit III
2 Marks Questions
- Define Suspension and enlist it’s ideal properties.
- Which factors influence the settling process in suspensions?
- Differentiate between flocculated and deflocculated suspensions.
- Write and explain stroke's equetion for theory of suspension sedimentation
- What is flocculaton and creaming in emulsions?
- Define microemulsion and multiple emulsions, providing examples for each.
- How can the stability of emulsions be maintained?
- Explain the concept of multiple emulsions.
5 Marks Question
- Explain the interfacial properties of suspended particles.
- Write note on Settling of Suspention with theories behind it.
- Write short note on Physical stability of Emulsion.
- Describe the HLB method for formulating emulsions.
- What are the rheological properties of emulsions and why are they important in formulation?
10 Marks Questions
- Discuss in detail the formulation techniques for suspensions.
- Discuss in detail theTheories of Emulsification.
Answer Keys :
2 Marks Questions:
Define Suspension and enlist its ideal properties.
- Suspension: A dispersion of solid particles in a liquid medium.
- Ideal properties: Homogeneity, stability, uniformity of particle size, and ability to redisperse upon agitation.
Which factors influence the settling process in suspensions?
- Factors: Particle size, particle shape, density difference between particles and medium, viscosity of the medium, and presence of flocculating agents.
Differentiate between flocculated and deflocculated suspensions.
- Flocculated suspensions have loosely aggregated particles forming flocs, whereas deflocculated suspensions have individual particles dispersed uniformly.
Write and explain Stoke's equation for the theory of suspension sedimentation.
- Stoke's equation: , where v is the settling velocity, g is the acceleration due to gravity, r is the radius of the particle, ρ is the density of the particle, ρf is the density of the fluid, and η is the viscosity of the fluid.
What is flocculation and creaming in emulsions?
- Flocculation: The process of aggregation of dispersed droplets in an emulsion.
- Creaming: The upward or downward movement of fat globules to form a cream layer on top or bottom of the emulsion.
Define microemulsion and multiple emulsions, providing examples for each.
- Microemulsion: Thermodynamically stable dispersion of oil and water stabilized by surfactants and cosurfactants (e.g., ointments).
- Multiple emulsions: Emulsions containing dispersed droplets of one emulsion within another (e.g., mayonnaise).
How can the stability of emulsions be maintained?
- By using emulsifiers, controlling particle size, adjusting pH, adding thickeners, and avoiding temperature extremes.
Explain the concept of multiple emulsions.
- Multiple emulsions contain droplets of one emulsion dispersed within another emulsion, forming a hierarchical structure.
Define Suspension and enlist its ideal properties.
- Suspension: A dispersion of solid particles in a liquid medium.
- Ideal properties: Homogeneity, stability, uniformity of particle size, and ability to redisperse upon agitation.
Which factors influence the settling process in suspensions?
- Factors: Particle size, particle shape, density difference between particles and medium, viscosity of the medium, and presence of flocculating agents.
Differentiate between flocculated and deflocculated suspensions.
- Flocculated suspensions have loosely aggregated particles forming flocs, whereas deflocculated suspensions have individual particles dispersed uniformly.
Write and explain Stoke's equation for the theory of suspension sedimentation.
- Stoke's equation: , where v is the settling velocity, g is the acceleration due to gravity, r is the radius of the particle, ρ is the density of the particle, ρf is the density of the fluid, and η is the viscosity of the fluid.
What is flocculation and creaming in emulsions?
- Flocculation: The process of aggregation of dispersed droplets in an emulsion.
- Creaming: The upward or downward movement of fat globules to form a cream layer on top or bottom of the emulsion.
Define microemulsion and multiple emulsions, providing examples for each.
- Microemulsion: Thermodynamically stable dispersion of oil and water stabilized by surfactants and cosurfactants (e.g., ointments).
- Multiple emulsions: Emulsions containing dispersed droplets of one emulsion within another (e.g., mayonnaise).
How can the stability of emulsions be maintained?
- By using emulsifiers, controlling particle size, adjusting pH, adding thickeners, and avoiding temperature extremes.
Explain the concept of multiple emulsions.
- Multiple emulsions contain droplets of one emulsion dispersed within another emulsion, forming a hierarchical structure.
5 Marks Questions:
Explain the interfacial properties of suspended particles.
- Interfacial properties include surface charge, surface area, surface energy, and adsorption of surfactants or polymers.
Write a note on the settling of Suspension with theories behind it.
- Theories: Stokes' law, hindered settling, and effect of Brownian motion, Sedimentation of flocculated particles. These theories explain the settling behavior of particles in a suspension under various conditions.
Write a short note on the physical stability of Emulsion.
- Physical stability refers to the ability of an emulsion to resist coalescence, creaming, or phase separation over time, which is achieved by proper formulation and emulsification techniques.
Describe the HLB method for formulating emulsions.
- The HLB (Hydrophilic-Lipophilic Balance) method involves selecting surfactants with appropriate HLB values to achieve the desired emulsion stability and characteristics.
What are the rheological properties of emulsions, and why are they important in formulation?
- Importance of flow properties, Influence on formulations, factors affecting rheological properties,
- Importance of flow properties, Influence on formulations, factors affecting rheological properties,
10 Marks Questions:
Discuss in detail the formulation techniques for suspensions.
- Formulation techniques include wetting of particles, controlled flocculation and flocculation in structured vehicle.
Discuss in detail the Theories of Emulsification.
- Theories include the monomolecular adsorption by surfactants, Multimolecular adsorption and film formation by hydrated lyophilic colloids, and solid particle adsorption.
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