AP Chem Chapter 9 Notes: Solids and Liquids Intermolecular Forces I.
II.
III.
IV.
Differences A.
Gases: very ____________________, particles move _________ and are _______________________.
B.
Liquid: ___________________, particles are ______________________________ but can still move.
C.
Solid: ________________ arrangement, particles are __________ and ___________________________.
A substance's state at a certain temperature depends on the particle’s ability to overcome ____________________________ forces. A.
Gases: kinetic energy of the particles is _____________________________________ than the intermolecular forces of the particles. Particles are _____________________.
B.
Liquid: kinetic energy of the particles is _____________than their intermolecular forces but not great enough for the particles to ________________________________ of each other. Particles are very ________________________________.
C.
Solid: kinetic energy of the particles is _________ than the intermolecular forces of the particles. Particles are in motion but it is _____________. They are arranged in a regular (_________________) or irregular (____________________) pattern. Particles are very ______________________________.
D.
Properties depend on the ________________ of ________________________ between the particles and their overall organization.
Intermolecular forces are _____________ than ionic/covalent bonds. A.
______________ energy is needed to _________or ____________ a substance than to actually break _______________.
B.
These forces influence __________________________________.
C.
Introducing: ___________________________ forces (intermolecular forces).
D.
At ________________________________ and _____________________________________, these forces become more important. (Remember real gases!?)
E.
_______________________________ explains the differences in ___________________.
Types of IMF A.
(London) dispersion forces: 1.
Occurs in _______ molecules, but it is the ______________________________ in _____________________molecules. Page 1 of 6
2.
Molecules that have _____________________________ moment can be ______________ to have one (they need to be close together). a. The electrostatic forces between the __________ and __________________ of molecules cause this. b. a.k.a_______________________________________.
3.
What is actually happening: a. the _________________ of all molecules, as they come into _______________________ with each other, become _____________________. b. a molecule’s _________________________ affects the ___________________ of the intermolecular forces.
4.
Strength of _____________________ force is directly proportional to molecular _______. Why? a. the ______________ a molecule is, the more __________________ it has. b. the more _______________ a molecule has, the more _______________________ it is!
B.
C.
V.
5.
__________ matters! More exposed surface = more contact = more induced _______________!
6.
______ matters! The presence of a pi bond increases ________________________.
Dipole-dipole forces: 1.
Occurs in ______________ molecules
2.
These are ________________ than dispersion forces.
3.
The larger the ____________moment(electronegativity difference), the stronger the ________.
Hydrogen bonding 1.
Occurs in ____________ molecules that have an H-N, H-O or H-F bond (___________!)
2.
__________________ than dipoledipole and dispersion forces.
3.
Because of the attraction b/w the ____ and the _________________ on a small electronegative atom (N, O, F!)
Relative Strength of IMFs A.
Hydrogen bonding > Dipole-dipole forces > London dispersion forces
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VI.
B.
If the type of intermolecular force is the same, molecular _______ will influence the boiling point. (more _____________________!)
C.
If type and size is the same, ____________ will influence the boiling point. (more _________________!)
Strength of intermolecular forces gives rise to certain ___________________ of liquids and solids. A. B.
As the __________________ of the intermolecular forces of a gas _________________, they deviate more from _______________ behavior.
Phase Changes I.
Phase change review (see chart to the right)
II.
Energy changes: A.
B. III.
1.
Heat of vaporization (ΔHvap): heat required to change a ____________ to a ___________ at its boiling point
2.
Heat of fusion (ΔHfus): heat required to change a ____________ to a _____________ at its melting point.
Temperature change ( _____________ areas)
Energy changes: A.
B. IV.
Phase change (temp stays ___________; _______ areas)
Phase change (temp stays constant; flat areas) 1.
Heat of vaporization (ΔHvap): heat required to change a liquid to a gas at its boiling point
2.
Heat of fusion (ΔHfus): heat required to change a solid to a liquid at its melting point.
Temperature change (sloped areas)
Heating/Cooling Curves (q or E vs. T): A.
Used for heat (q) problems involving phase changes.
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V.
B.
Example: Calculate the enthalpy change upon converting 1.00 mol of ice at -25°C to water vapor (steam) at 125°C under a constant pressure of 1 atm. The specific heats of ice, water, and steam are 2.09 J/g-K, 4.18 J/g-K and 1.84 J/g-K, respectively. For H2O, ΔHfus = 6.01 kJ/mol and ΔHvap = 40.67 kJ/mol.
C.
What is the enthalpy change during the process in which 100.0 g of water at 50.0°C is cooled to ice at –30.0°C? (Use the specific heats and enthalpies for phase changes given in Sample Exercise 11.4.)
Phase Diagrams (P v. T): A.
Lines (AD, AB, AC) represent points where phase _____________ or phase ___________________ occur.
B.
Triple point (A): P and T where _________ ______________________ are in equilibrium.
C.
Critical point (B): Created by the critical temperature and critical pressure. Above this point, __________ and __________ are indistinguishable.
D.
Melting points: Line AD.
E.
Boiling points: Line AB.
F.
Sublimation points: Line AC.
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Vapor Pressure I.
At any ________________________, some ____________ molecules have enough energy to _______________. A.
The pressure caused by these “escaped” molecules is known as ________________________________.
B.
As temperature _____________________, __________ molecules escape, _____________________ the vapor pressure.
II.
In a sealed container, the liquid and vapor are in dynamic ____________________________ (the substance ____________________ and _______________________ at the same rate)
III.
Boiling Point: _______________________ at which ______________ pressure equals ______________________ pressure. Normal boiling point: temperature at which ______________________________ equals ___________ (a.k.a. the pressure at _____________________).
IV.
Example: A.
Estimate the boiling point of diethyl ether under an external pressure of 0.80 atm.
B.
At what external pressure will ethanol have a boiling point of 60°C?
Solids I.
Look at the chart….
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II.
III.
V.
Answering AP questions: A.
Relate response to __________________________________________ and/or ___________________
B.
Many times, it's all about the ____________________ (_______________________________)!
C.
Memorize the covalent network solids:
Alloys: _____________________ of metals. A.
___________________________ alloy (One type of atom _________________ another in the metallic matrix). Ex:
B.
___________________________ alloy (One type of atom _____________________________ in a metallic matrix). Ex:
Special case: Semiconductors
silicon is “____________” with other _________________ to improve __________________________.
Polarity and Solubility I.
“Like dissolves like” (do not use these words on the AP exam – use technical terminology from below!) A.
____________ dissolves ____________ and ____________________ dissolves ____________________.
B.
Therefore, polar _________________________________ nonpolar and vice versa.
C.
Substances with similar ______________________________________________ tend to be ____________________________________ in one another.
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