Interface (chemistry)

An interface is a surface forming a common boundary between two different phases, such as an insoluble solid and a liquid, two immiscible liquids or a liquid and an insoluble gas. The importance of the interface depends on which type of system is being treated: the bigger the quotient area/volume, the more effect the surface phenomena will have. Therefore interfaces will be considered in systems with big area/volume ratios, such as colloids.

Interfaces can be spherical or flat, so they can be considered to be always spherical with finite or infinite radius. For example oil droplets in a salad dressing are spherical but the interface between water and air in a glass of water is mostly flat.

Surface tension is the function which rules interface processes.

Interfaces may cause various optical phenomena, such as refraction. Optical lenses serve as an example of a practical application of the interface between glass and air.

One important interface is the gas liquid interface between aerosols and other atmoshperic molecules; research on this portion of atmospheric chemistry is being conducted at the University of Wisconsin-Madison.