Post on 16-May-2015
Interparticle Forces and Phase Diagrams
Music: “Hold On Loosely”
by 38 Special
Forces of Chemistry and Physics
Interparticle Forces
Hydrogen “bridge”
page 178 middle
Requirements for a Hydrogen “Bond”
page 178 bottom
Four cases of Hydrogen “Bonding”page 179 bottom
Making surfaces more hydrophobic
Hydrogen bonding in DNA
Inorganic examples of H-bonding
Phase Transitions(Phase Changes)
Phase Diagrams(especially one-component P vs. T graphs)
Temperature vs. heat added graphshowing melting point & boiling point
-- Boiling point
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Heat involved (per gram) in the Phase Changes of Water
Phase transitions (Phase changes)
Summary of the Information Available in the CO2 Phase Diagram
Value of a Phase Diagram
3-D graph of ideal gas properties
A graph of three variables (such as P, V, & T)requires three dimensions and is often a surfacerather than a line as for the 2-D graphs.
A 3-D Phase diagram (with only one component):
A surface representing the properties of a typical pure substance(what a theoretical equation of state would have to account for)Each point on the curving surface represents a set of values of the pressure, temperature, and molar volume that can be attained by this substance.
Two-component Phase Diagrams
(Temp vs. Composition)
Gibbs’ Phase rule for a two-component system:F + P = C + 2, where C=2so, F + P = 2 + 2 = 4so, F = 4 – P
for one phase (P=1) F=3 which is a space, not restricted to the area of any 2-D graph.for two phases (P=2) F=2 which is an area or surfacefor three phases (P=3) F=1 which is a linefor four phases (P=4) F=0 which must be a point, such as an azeotrope or a eutectic point.