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.