Surface Tension
hydrophilic HLB is low or high?
HIGH
Tweens have low/high HLB?
High (9.6-16.7)
lipophilic HLB is low or high?
LOW
What is surface tension?
Molecules on top can only interact with the molecules below them. The molecules on top are pulled down because there are no molecules above them pulling upward. The surface contracts and results in surface tension.
If two liquids are completely mixed, is there any interfacial tension?
NO
the work required to increase surface A of the liquid by 1 area unit
Surface free energy
surface tension definition
The "tension" in the surface is the force per unit length that must be applied parallel to the surface as to counterbalance the net inward pull
T/F. Surface tension is greater than interfacial tension.
True
negative adsorption
added materials are partitioned more in favor of bulk
name some antifoaming agents?
alcohol, ether, castor oil, and some surfactants
Hydrogen bonding increases ____ in liquids?
cohesion
Surfactants that are used to remove dirt
detergents
relatively stable structure consisting of air pockets enclosed within thin films of liquid
foam
amphiphile
has affinity for both polar and non-polar groups
expansion of the surface increases/decreases the energy of the system?
increases
Force per unit length existing at the interface between two immiscible liquids
interfacial tension
spans have low/high HLB?
low (1.8-8.6)
foaming agent does what?
stabilizes the gas-in-liquid dispersion
Molecules or ions that are adsorbed at interfaces
surfactants or surface acting agents
positive adsorption
the added molecules are partitioned in the favor of the interface
most important property of a wetting agent?
to lower the contact angle between a liquid droplet and surface over where it spreads
surfactant that, when dissolved in water lowers the advancing contact angle and aids in displacing an air phase at the surface and replacing it with a liquid phase
wetting agent