11. Liquids, Solids, Intermolecular Forces Flashcards
ThermAl energy high relative to intermolecular forces then matter tends to be ____
Gaseous
Thermal energy low relative to intermolecular forces then matter tends to be ____
Liquid or solid
Solid and liquid densities are ____ than gas
Greater
Thermal energy ___ attractions between a molecules in a liquid
Overcomes
Liquids
Not easily compressed
Molecules are in close contact
High density
Moderate IMF
Gas
Easily compressed
Become gas at higher temperatures or reduced pressure
Molecules stay in tact but break IMFs
Solid
Not compressible
Solid at cooler temperatures
May be crystalline(well ordered 3D array) or amorphous(no order)
At room temperature moderate to strong IMFs tend to be____ and have high melting and boiling points
Liquids or sounds
At room temperature weak IMFs tend to be____ and have low melting and boiling points
Gaseous
Binding forces are ___ IMFs because _____
Stronger than; they have large charges(protons and electrons) interacting closely
IMFs are ____ binding forces because ____
Weaker than; because smaller charges at higher distances
Dispersion forces
. Exist in all molecules
. Result in electrons being unevenly distributed causing an instantaneous dipole
. The magnitude of the forces depends on size of molecule( bigger molecule means electrons are more shielded from nucleous)
. As dispersion force increase (bigger molar) boiling point increases
Shape matters if there is more area to interact
Dipole-dipole forces
.exist in polar molecules
.polar ends create slightly charged ends attracting other polar molecules
. Stronger than dispersion forces
. Has to have net dipole
Hydrogen bonding
. Occurs when a polar molecule contains an H bonded to F O N
. Hydrogen carries large partial positive charge when bonded to these molecules
. Also small distances create stronger bonds
Ion-dipole forces
Positive ions interacting with polar ends of molecules
Strongest of all IMFs
Surface tension
Energy required to increase surface area
Oscillating
Move back and forth at regular speed
Vaporization
Thermal energy overcoming intermolecular forces. Endothermic(requires heat). Liquid to gas
Higher temperature results in —- average energy for the molecule
Higher
Condensation
Molecules plunge back into substance; lower end of energy curve. Exothermic releases heat( steam on hand) gas to liquid
Volatile
Easily evaporate( weak IMFs) low boiling
Heat of vaporization
Amount of heat requires to vaporize one mole of liquid to a gas(always positive because it is absorbing) if substance is hotter the Hvap can be lower because less heat is required. Units: kj/mole
Dynamic equilibrium
Rate of condensation and vaporization becomes constant. In sealed container at constant temperature
Vapor pressure
Pressure of gas in dynamic equilibrium with liquid. Depends on IMFs and temperature
Le chatelier princple
When a system in dynamic equilibrium is disturbed it will minimize or maximize to return to equilibrium
Temperature and vapor pressure
As temperature increases vapor pressure increases, it allows more molecules to vaporize
Boiling point
Temperature at which vapor pressure equals external pressure(allows molecules to break free from interior not just surface) no external pressure pushing down
