Therm Sec 15
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1. Define True Solution
One-phase system where the solute particles consist of individual molecules or ions. Considered homogeneous.
2. Define Colloidal Dispersion
AKA. Colloids. The suspended particles have diam. 0.001 um - 1 um. Between homo and heterogeneous solutions.
3. Define Disperse Phase
The aggregate of particles. Analogous to the solute of a homogeneous sol'n.
4. Define Dispersion Medium.
Medium where particles are dispersed. Analogous to solvent in homogeneous sol'n.
5. Define Disperse System.
Complete colloidal system. Analogous to the term solution.
6. Define Colloidal Dispersion.
Particles of disperse phase may contain more then 1 molecule but cannot be seen by microscope.
7. Define Suspension.
Particles of disperse phase contain more then 1 molecule and can be seen by eye and microscope.
8. Define Emulsion.
Particles of disperse phase are liquid droplets and the dispersion medium is a second liquid.
9. Define Emulsifying Agent.
A third substance is added to an emulsion to keep the two fluids suspended.
10. List 3 general classes of Colloids.
- Colloidal dispersions (or disperse systems).
- Associated colloids
- Macromolecular solutions
11. Give 1 optical method of detecting a colloidal system.
12. Why can't optical microscopes & filter papers be used to detect colloidal systems?
Particles are too small to be seen by microscope or to be stopped by filter paper
13. What is a gel and 1 example.
- Liquid (disp phase) and solids (disp medium).
- Ex. Agar
14. What is foam and 1 ex.
- Gas (disp phase) and liquid (disp medium).
- Ex. Whipped cream
15. What is an aerosol and 1 ex.
- Solid (disp phase) and gas (disp medium).
- Ex. Smokes
16. What is an emulsion and 1 ex.
- Liquid for both disp phase and disp medium.
- Ex. Oil & water
17. What is a sol and 1 ex.
- Solid (disp phase) and liquid (disp medium).
- Ex. AgCl
18. What are 2 ways of preparing a sol.
Dialysis & electrodialysis.
19. Explain why properties of colloids can be explained by the nature of their surfaces etc. (sp10)
Surf area/mass ratio is so large w colloids that it outweighs all other properties
20. Define hydrophobic
21. Define hydrophilic
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