3. Main forces that affect the colloids system…Van Der Waals attractive forceselectrostatic repulsive forces
4.
5. DLVO THEORY The DLVO theory, named after the two Russian scientists (Derjaguin and Laudau) and the two Dutch scientists (Verwey and Overbeek) who developed it around the 1940’s, is a corner stone of colloid science.
11. For small distances, the sum of the two energies is always – ve (i.e. net attractive) ⟹ cause aggregation When the sum of two energies is + ve ⟹ repulsive force
13. Development of a net charge at the particle surface affects the distribution of ions in the surrounding interfacial region, resulting in an increased concentration of counter ions (ions of opposite charge to that of the particle) close to the surface Thus an electrical double layer exists round each particle An electrical double layer exists around each particle.
14. The liquid layer surrounding the particle exists as two parts; an inner region (Stern layer) where the ions are strongly bound and an outer (diffuse) region where they are less firmly associated Within this diffuse layer is a notional boundary known as the slipping plane, within which the particle acts as a single entity The potential at this boundary is known as the zeta potential
19. When the potential is low, attraction exceeds repulsion and the dispersion will break and coagulate. Considered as not stable. When the potential is high, repulsion force is higher than attraction force, the dispersion is considerable stable.
