Stabilization and Destabilization of Dispersions

Question 1

What factors affect the rate of sedimentation or creaming in dispersions?

Answer 1

The density difference between the discontinuous and continuous phases and the viscosity of the continuous phase.

Question 2

Differentiate between flocculation and coalescence.

Answer 2

Flocculation is reversible and involves droplets clumping together without merging, while coalescence is irreversible, resulting in two droplets merging into one.

Question 3

What is partial coalescence?

Answer 3

Partial coalescence occurs when droplets come into contact and share a small interface area while remaining distinct, often seen in partly crystalline dispersed phases.

Question 4

What is phase inversion in emulsions?

Answer 4

Phase inversion is when the concentration of the dispersed phase is similar to the continuous phase, causing an emulsion to switch from oil-in-water to water-in-oil.

Question 5

How does increasing the viscosity of the continuous phase affect dispersion stability?

Answer 5

Increasing viscosity slows the rate of sedimentation and creaming, enhancing the stability of the dispersion.

Question 6

How does temperature affect phase inversion in emulsions?

Answer 6

Phase inversion is temperature-dependent, and changes in temperature can influence the stability and behavior of the emulsion.

Question 7

What role do stabilizing molecules play in dispersions?

Answer 7

Stabilizing molecules help maintain the interface between dispersed and continuous phases, preventing coalescence and promoting stability.