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Terms in this set (23)
Hydrogen bonding increases ____ in liquids?
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.
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
Force per unit length existing at the interface between two immiscible liquids
If two liquids are completely mixed, is there any interfacial tension?
Surface tension is greater than interfacial tension.
the work required to increase surface A of the liquid by 1 area unit
Surface free energy
expansion of the surface increases/decreases the energy of the system?
the added molecules are partitioned in the favor of the interface
added materials are partitioned more in favor of bulk
Molecules or ions that are adsorbed at interfaces
surfactants or surface acting agents
has affinity for both polar and non-polar groups
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
most important property of a wetting agent?
to lower the contact angle between a liquid droplet and surface over where it spreads
Surfactants that are used to remove dirt
relatively stable structure consisting of air pockets enclosed within thin films of liquid
foaming agent does what?
stabilizes the gas-in-liquid dispersion
name some antifoaming agents?
alcohol, ether, castor oil, and some surfactants
spans have low/high HLB?
Tweens have low/high HLB?
lipophilic HLB is low or high?
hydrophilic HLB is low or high?
Read Slides 17 and 18 on surface tension