Lecture Notes Chem 150 - K. Marr. Chapter 12 Intermolecular Attractions & the Properties of Liquids & Solids Silberberg 3 ed. Intermolecular Forces: Liquids, Solids, and Phase Changes. 12.1 An Overview of Physical States and Phase Changes 12.2 Quantitative Aspects of Phase Changes
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Intermolecular Attractions &
the Properties of Liquids & Solids
Silberberg 3 ed
12.1 An Overview of Physical States and Phase Changes
12.2 Quantitative Aspects of Phase Changes
12.3 Types of Intermolecular Forces
12.4 Properties of the Liquid State
12.5 The Uniqueness of Water
12.6 The Solid State: Structure, Properties, and Bonding
12.7 Advanced Materials
A Macroscopic Comparison of Gases, Liquids, and Solids
Shape and Volume
Ability to Flow
Conforms to shape and volume of container
Conforms to shape of container; volume limited by surface
Maintains its own shape and volume
Liquid: Conforms to shape of container; volume limited by surface
Solid: Maintains its own shape and volume
Gas: Conforms to shape and volume of container
Particles close together in S’s and L’s
e.g. Water vs Carbon Dioxide(sublimes. @ -58.5 oC)
e.g. density, mp, bp, solubility, vapor pressure, etc.
Covalent bonds>>>>>Hydrogen bonding>>
Dipole-dipole interactions>>>>> London forces
e.g. DNA, proteins
Cyclopentane, BP = 49.3 oC
e.g. Halogens and noble gases
What is happening in to KE and PE at each part of the curve?
DHvap = + 40.7 kJ/mol
Heat absorbed when one mole liquid is changed to one mole of vapor at constant T and P
Heat absorbed when 1 mole solid is changed to 1 mole of liquid at constant T and P.
Within a phase
A change in heat is associated with a change in average KE and, therefore, a change in temperature.
q = (mass)(Specific Heat)(Dt)
During a phase change
A change in heat occurs at constant temperature, which is associated with a change in PE, as the average distance between molecules changes--Bond IMF formation is exothermic, IMF breaking is endothermic
q = (moles of substance)(enthalpy of phase change)
Why are raindrops spherical?
Liquids minimize surface area by forming spherical surfaces Lowers PE, thus increases stability ( e.g. Raindrops, overfilled glass)
Where molecules leave surface and enter vapor space around them
S L G or S G
Pressure exerted by a vapor in a closed flask in equilibrium w/ its liquid(T11)
Ln P = -DHvap/RT + constantor
Ln (P1/P2) = -DHvap /R(1/T2 - 1/T1)
Note: P = Vap Pressure; R = 8.314 J/mol K
ln P = -DHvap/RT + c
P = Vapor Pressure R = 8.314 J/mol K
Interpret phase diagrams and show how a phase diagram can be used to represent the thermodynamic relationship between the three states of matter for a particular substance.
Used to decaffeinate coffee and tea
Describe the use of X-Ray diffraction to determine the structure of crystals (T23a)
Objective: Relate the properties of solids to crystal type
E.g. Problems 12.90 and 12.91, page 480 Silberberg 3rd ed.
E.g. Problem 12.93, page 480 Silberberg 3rd ed.
(divide the mass of the atoms per unit cell by the volume of the unit cell)