Surfactants Flashcards
What is a surfactant?
Surface + active + agent
Phase boundaries..
Interface:
boundary between two phases
Phase boundaries..
Surface:
boundary between two phases, one of which is a gas
Energy is..
the capacity to do work
Surface energy..
potential energy per unit surface area
What does intermolecular bonding do to molecules?
Intermolecular bonding stabilises molecules and lowers their energy.
Surface tension…
energy required to expand the surface of a liquid by a unit area (N m−1 or dyn cm−1).
For liquids, surface tension and surface energy are…
quantitatively equivalent and often used interchangeably.
What do surfactants do?
reduce suface tension
Contact angle is…
Indicator of solid surface wettability
Wettability is…
Tendency of liquid to adhere to solid surface
Amphiphilic means..
has both hydrophilic (water-loving) and hydrophobic (water- hating) portions in the same molecule.
Uses of surfactants (3)
wetting agent
emulsifying agent
foaming agent
Micelles form when…
When the liquid surface is saturated with surfactant molecules, excess surfactant molecules sink below the liquid surface and self-aggregate into micelles.
Critical micelle concentration (CMC)
Minimum surfactant concentration at which micelles begin to form.
Generally, the larger the surfactant molecule, the lower the molar CMC.
