Exam 1, Wed 422

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Exam 1, Wed 4-22

• Chapter 13 13.10 13.13
• Chapter 14 14.1 14.5 (no spectroscopy on
  test)
• Chapter 16
• 16.1 16.2
• Types of solids (found in 16.3, 16.6)
• 16.10 16.11
• know how to use equation 16.5
• Multiple Choice, No Notes
• Practice Exams Webassign, van Koppens Spring
  06 (coursepages archives Chem 1C/1CL
  Quizzes Exams)

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Crystalline Solids Long range order
Molecular Solids Composite units are
molecules low m.p.
Ionic Solids Composite units are cations and
anions high m.p.
Atomic Solids Composite units are atoms variable
m.p.
m.p. melting point
Covalent high m.p.
Nonbonding very low m.p.
Metallic variable m.p.
Examples What type of solid is formed
by H2O Cl2 Ar Cu Cdiamond
For example Webassign wants both atomic and
metallic for Au
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FYI

• Covalent Bonding sharing electrons
• Ionic Bonding opposite charged ions
• Metallic Bonding sea of electrons

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?Hvap and ?Hfus

• ?Hvap Amount of heat to vaporize 1 mol of liquid
• ?Hfus Amount of heat to melt 1 mol of solid
• Both increase with increasing IMF
• More energy required to break stronger IMF

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Dynamic Equilibrium
Initially
After Some Time
Vaporization, Evaporation
Vacuum
Condensation
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Dynamic Equilibrium
Pressure at equilibrium is the Vapor Pressure of
the Liquid
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Vapor Pressure

• Pressure of a vapor in equilibrium with its
  liquid
• Liquids with high vapor pressure are volatile
• Vapor pressure increases with decreasing IMF
• Less forces to break to escape into gas phase
• Vapor pressure increases with temperature

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Vapor Pressure vs. Temperature
Boiling Point When vapor pressure equals
atmospheric pressure
Pvap (torr)
ln(Pvap )
1/T (K)
Temperature (C)
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From Graph
To calculate changes in Pvap at different
Temperatures Solve for C
Rearrange
Eq. (16.5)
In Kelvin!
Solve Problems 1) What is the boiling point of
water at 270 torr? ?Hvap for water is 40.7
kJ/mol
2) A substance has a vapor pressure of 81.3 torr
at 30C and 208 torr at 50C. What is ?Hvap for
this substance?
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Adding Heat to Water
140 120 100 80 60 40 20 0 -20
Steam
q nC?T
Water Steam
q n ?Hvap
Temperature (C)
Water
q nC?T
q n ?Hfus
Ice Water
Ice
Amount of Heat Added
q nC?T
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Phase Diagrams - Water
Supercritical Fluid
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Phase Diagrams - Water
This negative slope is unique to water, and
useful!
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Phase Diagrams Carbon Dioxide