6053046
Description
Flashcards by Hashala Fernando, updated more than 1 year ago
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Created by Hashala Fernando
over 8 years ago
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| Question | Answer |
| Tension | water molecules pulling in against each other. |
| Exceptions | surface molecules being exposed to the air (hydrophobic) |
| interfacial tension | attractive force between the molecules at the air/water interface |
| surface tension | when one interface is a liqud and he other is a gas, it is referred to as the surface tension |
| Emulsions | contain one liquid finely dispensed in a second liquid they are usually o/w but may be in oil w/o or even multiple phases Eg: milk mayonaise salad dressing ice cream chocolate cosmetics |
| emulsifiers | most commonly surfactants they lower the interfacial tension between the oil and water making it easier to form and emulsion |
| Surfactants- emulsifiers | |
| Surfactants- emulsifiers | lowering the interfacial tension also makes it easier to break the emulsion Surfactants help to stabilise an emulsion against breaking by adsorbing at the oil- water interface and preventing that interface from deforming or breaking. |
| Surfactants- Coalescence | |
| Stability from surfactants | |
| HLB Number- Hydrophobic Lipophilic Balance | The balance between the hydrophobic and lipophilic parts of a surfactant surfactants have a genuine HLB number oils have a required HLB number if the oil's HLB and the surfactant's HLB match, then the emulsion will be most stable |
| HLB of a surfactant | |
| Emulsification | Surfactants can: Stabilise an o/w emulsion Stabilise a w/o emulsion solubilise the oil- by forming a micelle |
| General requirements of an emulsification | reduce the interfacial tension adsorbs at the interface quickly resists thinning when droplets collide should be slight;y more soluble in the continuous face aid stability of flocculation aid stability to coagulation increase bulk viscosity perform well at low concentration be inexpensive GRAS- generally recognised as safe be chemically compatible with the oil work! |
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