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Questions and Answers
What is the main cause of non-wetting in a liquid-solid particle system?
What is the main cause of non-wetting in a liquid-solid particle system?
- Lack of Brownian motion
- Insufficient dispersion of solid particles in the liquid (correct)
- Inadequate gravitational effects
- Excessive dispersion of solid particles in the liquid
What type of forces lead to repulsion between like particles in a suspension?
What type of forces lead to repulsion between like particles in a suspension?
- London dispersion forces
- Electrostatic forces (correct)
- Van der Waals forces
- Hydrogen bonding
What factor contributes to the thermodynamic instability of a system when particles are dispersed into a liquid?
What factor contributes to the thermodynamic instability of a system when particles are dispersed into a liquid?
- Decrease in interfacial area
- Increase in Van der Waals forces
- Decrease in overall free energy
- Increase in overall free energy (correct)
What is the main cause of particle agglomeration in a liquid-solid system?
What is the main cause of particle agglomeration in a liquid-solid system?
What can greatly affect the zeta potential of a particle and ultimately the stability of the system?
What can greatly affect the zeta potential of a particle and ultimately the stability of the system?
In a deflocculated system, what type of forces predominate over repulsive forces for the particles?
In a deflocculated system, what type of forces predominate over repulsive forces for the particles?
What is the sedimentation volume (F) when a system is in flocculation equilibrium?
What is the sedimentation volume (F) when a system is in flocculation equilibrium?
What happens to the sedimentation volume (F) when an appropriate amount of flocculating agent is added?
What happens to the sedimentation volume (F) when an appropriate amount of flocculating agent is added?
What does the Stokes Equation describe?
What does the Stokes Equation describe?
What does the sedimentation rate (v) depend on according to the Stokes Equation?
What does the sedimentation rate (v) depend on according to the Stokes Equation?
What are the limitations of the Stokes Equation?
What are the limitations of the Stokes Equation?
How can flocculation be controlled?
How can flocculation be controlled?
What is colloidal stability defined as?
What is colloidal stability defined as?
What influences the electrical repulsion between particles?
What influences the electrical repulsion between particles?
What is the role of zeta potential in colloidal stability?
What is the role of zeta potential in colloidal stability?
What is the conventional belief about the position of the shear plane?
What is the conventional belief about the position of the shear plane?
What is the primary driving force for aggregation?
What is the primary driving force for aggregation?
What must be introduced to prevent particle aggregation?
What must be introduced to prevent particle aggregation?
What measures the surface potential of particles?
What measures the surface potential of particles?
What is the function of electric and steric repulsive barriers?
What is the function of electric and steric repulsive barriers?
What is the role of the electric double layer in particle stability?
What is the role of the electric double layer in particle stability?
What is the significance of the potential-determining ion and the counterion?
What is the significance of the potential-determining ion and the counterion?
What does zeta potential measure at the shear plane?
What does zeta potential measure at the shear plane?
What is the primary cause of phase separation in a dispersion system?
What is the primary cause of phase separation in a dispersion system?
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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
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