Thermodynamics of Surfaces and Interfaces. What is thermodynamics dealing with?. Thermodynamics is the branch of science that id concerned with the principles of energy transformation in macroscopic system. - PowerPoint PPT Presentation
Thermodynamics of Surfaces and Interfaces
Thermodynamics of Surfaces and InterfacesWhat is thermodynamics
dealing with?Thermodynamics is the branch of science that id
concerned with the principles of energy transformation in
macroscopic system.Macroscopic properties of matter arise from the
behavior of a very large number of molecules.Thermodynamics is
based upon experiments and observation , summarized and generalized
in the laws of thermodynamics.These laws are not derivable from any
other principles: they are in fact improvable and therefore can be
regarded as assumptions only.
Some DefinitionsIntensive variablesExtensive variables System,
isolated, open, closedSurroundingsBoundaryEquilibrium
ProcessThermodynamic stateEquilibrium between phases in
heterogeneous closed systemWhat does equilibrium mean?A system is
in eq if no further spontaneous changes takes place and if the same
state can be reached by other directions.A phase?A phase
equilibrium is defined when the same species are present in
different phases.A heterogeneous closed systems is composed of two
or more phases, with each phase is considered as an open system
within an overall closed system.Equilibrium between phases in
heterogeneous closed systemIf the system initially, is not in an
internal eq, then any process should occur in irreversible
direction.So, according to first law:
And, combining with Clausius inequality: (for both reversible
and irreversible processes)
Equilibrium between phases in heterogeneous closed systemOr
finally:
Equilibrium between phases in heterogeneous closed system
Equilibrium between phases in heterogeneous closed system
Equilibrium between phases in heterogeneous closed system
Equilibrium between phases in heterogeneous closed system
Equilibrium between phases in heterogeneous closed system
Equilibrium between phases in heterogeneous closed system
Wettability and Contact AngleReference:
Wettability and contact angle
In the case of a liquid that forms a uniform film (i.e., where =
0), the solid is said to be completely wetted by the liquid, or
that the liquid wets the solid.Where a nonzero angle is formed,
there exists some controversy as to how to describe the system. If
a finite contact angle is formed (> 0), some investigators
describe the system as being partially wetted.Others prefer to make
a distinction based on the size of the contact angle. For example,
a given worker may define as wetting any liquid that produces a
contact angle of 30 or less on a solid. Between 30 and 89 the
system would be partially wetting, and 90 and above nonwetting.
Alternatively, any system with 0
