24 Questions
What is the main cause of non-wetting in a liquid-solid particle system?
Insufficient dispersion of solid particles in the liquid
What type of forces lead to repulsion between like particles in a suspension?
Electrostatic forces
What factor contributes to the thermodynamic instability of a system when particles are dispersed into a liquid?
Increase in overall free energy
What is the main cause of particle agglomeration in a liquid-solid system?
Creation of a large interfacial area
What can greatly affect the zeta potential of a particle and ultimately the stability of the system?
Electrolytes, pH, and other molecules that can adsorb to the interface
In a deflocculated system, what type of forces predominate over repulsive forces for the particles?
Attractive forces
What is the sedimentation volume (F) when a system is in flocculation equilibrium?
1
What happens to the sedimentation volume (F) when an appropriate amount of flocculating agent is added?
It results in the maximum sedimentation volume
What does the Stokes Equation describe?
Rate of sedimentation/creaming for spherical particles in a very dilute suspension
What does the sedimentation rate (v) depend on according to the Stokes Equation?
Particle size and the difference in density between the particle and the liquid
What are the limitations of the Stokes Equation?
Applies only to spherical particles in a very dilute suspension
How can flocculation be controlled?
By adding electrolytes and/or polymers to a deflocculated system
What is colloidal stability defined as?
Prevention of particle aggregation in dispersions
What influences the electrical repulsion between particles?
Presence, concentration, and valence of counterions
What is the role of zeta potential in colloidal stability?
Measuring the surface potential of particles and ensuring stability
What is the conventional belief about the position of the shear plane?
Close to the Stern plane
What is the primary driving force for aggregation?
Stronger intermolecular forces
What must be introduced to prevent particle aggregation?
Repulsive interactions
What measures the surface potential of particles?
Zeta potential
What is the function of electric and steric repulsive barriers?
Preventing the formation of hard cakes in dispersions
What is the role of the electric double layer in particle stability?
Plays a critical role in particle stability
What is the significance of the potential-determining ion and the counterion?
Influencing the zeta potential
What does zeta potential measure at the shear plane?
Surface potential of particles
What is the primary cause of phase separation in a dispersion system?
Weak intermolecular forces leading to flocculation
Study Notes
Colloidal Stability and Particle Interactions
- Particles in a dispersion system tend to form agglomerates to decrease surface area, leading to phase separation
- Flocculation occurs due to weak intermolecular forces, while aggregation is driven by stronger forces
- Colloidal stability is defined by the prevention of particle aggregation in dispersions
- To prevent aggregation, repulsive interactions must be introduced to overcome the thermodynamic tendency
- Electric and steric repulsive barriers can prevent the formation of hard cakes in dispersions
- Zeta potential measures the surface potential of particles and is crucial for stability
- Electrical repulsion between particles is influenced by the presence, concentration, and valence of counterions
- The electric double layer, including the Stern plane and shear plane, plays a critical role in particle stability
- Zeta potential is dependent on the amount of absorbed counterions and is measured at the shear plane
- Zeta potential is important for understanding and ensuring the stability of dispersed systems
- The potential-determining ion and the counterion influence the zeta potential
- The exact position of the shear plane is not known, but it is conventionally believed to be close to the Stern plane
Test your understanding of colloidal stability and particle interactions with this quiz. Explore concepts such as agglomeration, flocculation, and aggregation, and learn about the crucial role of zeta potential and electric double layer in preventing particle aggregation in dispersions.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
