Studied by 14 people
States
______________ depend on the balance between kinetic energies of particles and interparticle energies of attraction.
Gases
Highly compressible & assume shape/volume of their container.
Molecules are far apart and do not interact much.
Liquids
Almost incompressible and assume the shape, but not volume, of their container.
Molecules held more closely together, but not so rigid that the molecules cannot move.
Solids
Incompressible and have a definite shape/volume.
Molecules are packed closely together (extremely rigidly).
condensed
Solids and liquids are _____________ phases.
Crystalline
Solids with highly ordered structures.
cooling or compressing
Gas → Liquid → solid
This conversion can be achieved by…
heating or reducing pressure
Solid → Liquid → gas
This conversion can be achieved by…
Intermolecular Forces
Forces between molecules that hold them together (many physical properties are caused by these…)
Intramolecular Forces
Forces between bonds (i.e. covalent, ionic, metallic)
[These do NOT break with state changes]
intramolecular
Which is stronger, Intermolecular or Intramolecular?
direct
Boiling point and Attractive Forces have an/a __________ relationship.
BP+, AF+
direct
Melting Point and Attractive Forces have a/an _______________ relationship.
MP+, AF+
bigger charges, closer molecules
Why are intramolecular forces stronger?
Dispersion
Intermolecular force resulting from shifting electron clouds (neutral non-polar atoms and/or molecules).
direct
Relationship between dipole moment and boiling point/forces.
DM+, BP/AF +
momentary dipole
The movement of electrons when attractions happen in Dispersion causes a ____________ ____________.
Polarizability
The ease with which an electron distribution can be deformed (“squashiness” of its electron cloud)
direct
Relationship between polarizability and dispersion forces.
P+, DF+
Relationship between weight/area of a molecule and dispersion forces.
W/A +, DF+
smaller
Dispersion forces between spherical molecules are _____________ than those between more cylindrically shaped molecules (due to more molecular contact).
Dipole-Dipole
Force existing between neutral polar molecules in which there is attraction of the + end of one polar molecule to the - end of another polar molecule.
higher
The ___________ boiling point reflects the dipole-dipole interactions present.
dipole moment
Compounds consisting of atoms with different electronegativities may have a _______________/partial charge caused by electron asymmetry.
increasing
If two molecules have about the same mass/size, then the strength of the intermolecular attractions between them increases with _______________ polarity.
direct
Relationship between polarity and intermolecular attractions.
P+, IA+
Hydrogen Bonding
Intermolecular force containing polar molecules with H-F, H-O, and H-N.
high
Boiling points of compounds with H-F, H-O, and H-N are abnormally _________.
small electronegative element
For Hydrogen Bonding, H must be bonded to a _________ ________________ __________.
unshared electron pair
Also, for Hydrogen Bonding, there must be an _______________ _____________ _________ on a nearby small electronegative ion/atom.
weaker
Hydrogen bonds are much ____________ than ordinary chemical bonds.
Ion-Dipole Forces
Intermolecular force being an interaction between an ion and the partial change on the end of a polar molecule.
direct
Relationship between magnitude, ionic charge, and dipole magnitude.
M+, IC+, DM+
dispersion forces
the strength of ____________ ______________ depends on molecular shapes and molecular weights.
polar
Dipole-dipole forces are found ONLY in ___________ molecules.
dispersion < dipole-dipole < hydrogen bonding < ion-dipole
List the 4 Intermolecular forces in order of increasing strength:
dispersion forces
If the molecules of two substances have similar molecular weights and shapes, ____________ _________ will be similar in magnitude.
stronger
The greater the molecular polarity, the _____________ the intermolecular forces.
higher
Intermolecular attractive forces will generally be greater in the substance with the ______________ molecular weight.
Viscosity
The resistance of a liquid to flow.
direct
Relationship between number of branches and viscosity (because of entanglement)
B+, V+
direct
Relationship between intermolecular force strength and viscosity.
IF+, V+
indirect
Relationship between viscosity and temperature.
V+, T-
Surface Tension
The amount of energy required to increase the surface area of a liquid by a unit amount.
higher
Stronger intermolecular forces cause ____________ surface tension.
cohesive forces
Intermolecular forces that bind molecules to one another.
adhesive forces
Intermolecular forces that bond molecules to a surface.
greater
If adhesive forces are _____________ than the cohesive forces, the meniscus is u-shaped (concave up).
weaker
If adhesive forces are _____________ than the cohesive forces, the meniscus is concave down.
liquid stops rising
What happens when cohesive forces = adhesive forces?
Capillary Action
The rise of liquids up very narrow tubes (climbs until adhesive and cohesive forces are balanced).
Endothermic
Reactions where energy is ADDED (absorbs energy from surroundings)
BREAKING bonds!!
Reactions generally get cold.
Exothermic
Reactions where energy in RELEASED to the surroundings.
MAKING/FORMING bonds!!
Reactions generally get warm.
exothermic
Gas → Liquid → Solid [endo/exo?]
endothermic
Solid → Liquid → Gas [endo/exo?]
vaporization
Which is larger, ∆H(fus) or ∆H(vap)?
(think about intermolecular attractions)
Sublimation, endothermic
Solid → Gas [name, endo/exo]
Fusion, endothermic
Solid → Liquid [name, endo/exo]
Vaporization, endothermic
Liquid → Gas [name, endo/exo]
Deposition, exothermic
Gas → Solid [name, endo/exo]
Condensation, exothermic
Gas → Liquid [name, endo/exo]
Freezing, exothermic
Liquid → Solid [name, endo/exo]
Heating curve
Plot of temperature change (y) versus heat added (x).
No
Does adding heat cause a temperature change during a phase change?
(think about intermolecular bonds)
Supercooling
______________ occurs when a liquid is cooled below its freezing point and still remains a liquid.
Critical Temperature
The highest temperature at which a substance can exist as a liquid.
Critical Pressure
The pressure required for liquefication at this critical temperature.
higher
The greater the intermolecular forces, the _____________ the critical temperature.
Supercritical Fluid
A substance at temperatures and pressures higher than its critical temperature and pressure in a state.
increase
As the number of molecules in the gas phase ______________, some of the gas phase molecules strike the surface and return to the liquid.
Vapor pressure
The pressure of a vapor
Dynamic Equilibrium
A condition in which two opposing processes occur simultaneously at equal rates.
Vapor Pressure of a liquid
The pressure exerted by a vapor when the liquid and vapor are in dynamic equilibrium.
volatile
A liquid that evaporates easily is said to be _____________.
direct
Relationship between temperature, AKE, and volatility.
T+, AKE+, V+
indirect
Relationship between Intermolecular Forces and Vapor Pressure.
IF+, VP-
indirect
Relationship between boiling point and volatility.
BP+, V-
Boiling point
The temperature at which the external pressure at the liquid surface equals the vapor pressure.
Normal boiling point
The boiling point of a liquid at 760 mm Hg (1 atm).
increases
The temperature of the boiling point ____________ as external pressure increases.
increase temperature, decrease pressure
What are the two ways to get a liquid to boil?
Phase diagram
A plot of pressure (y) versus temperature (x) summarizing all equilibria between phases.
This diagram tells us which phase will exist at a given temperature and pressure.
Vapor Pressure Curve
Curve where, generally, as temperature increases the vapor pressure increases.
Critical Point
Point representing the critical temperature and pressure for the gas.
Sublimation curve
Curve separating the solid and gas phases.
Melting curve
Curve separating the solid and liquid phases.
Normal melting point
Melting point at 1 atm
Triple point
Point representing when the temperature and pressure of ALL THREE phases are in equilibrium.
