Liquids,Solids, Intermolecular Forces

condensed states

• liquid and solids-more similar to each other than gas bc particles are close to each other

• more dense

Gas

• atoms or molecules are separated by large distances and don’t interact w each other much

• easily compressed bc have huge space btwn them→ easily forced into smaller volume

Density

degree of compactness

Most solids are slightly denser than liquids except for ice and water

True

Liquid

• particles can freely move around one another

• high density

• indefinite shape (takes shape of container)

• definite volume

• moderate intermolecular force strength force

  • not easily compressed bc their particles are already close tgr

Solid

• high density

• definite shape

• definite volume

• strong strength of intermolecular force (relative to thermal energy)

• particles fixed in place

Vaporization

• transition from liquid to gas

• thermal energy overrides IMF

• occurs faster with higher surface area

Crystalline

• well ordered 3D array, solid particles

Amorphous

• non-long-range order of solid particles

Intermolecular Force

• holds condensed states together

• attractive forces that exist btwn particles that compose a sample of matter

• moderate to strong blank make liquid or solid but weak blank make gas

Dispersion Forces

• present in all molecules

• result of fluctuations in electron cloud

  • All molecules have electrons

  • partial positive & negative (instantaneous dipole)

• as molar mass increases, blank strength increases (as well as boiling pt)

Dipole Dipole Force

• present in all polar molecules (bc of permeant dipoles)

Hydrogen Bond

• present in all polar molecules that have H bond directly to F, O, or N

• due to strong dipole moment that forms btwn atoms

ex) CH3CH2OH

instantaneous dipole

• instantaneous separation of charge

• dispersion force occurs bc fluctuations in electron cloud which result in blank

To polarize

• to form a dipole moment

• how easy molecules move

• depends on size of electron cloud

• larger electron cloud→ larger dispersion force

condensation

transition from gas to liquid

Rate of vaporization increases with

• increasing temperature

• increasing surface area (covers more ground)

• weaker IMF/decreasing IMF strength (bc weaker the molecular attraction→ easier to break free)

Vapor pressure

• pressure of gas in dynamic equilibrium with its liquid

• increases w increasing temp

• increases w decreasing strength of IMF(easier for molecule to break free and enter gas state)

• independent (not affected by) of surface area

  • rate of condensation and vaporization increase so cancel out

Dynamic equilibrium

• rate of evaporation equals rate of condensation

volatile

liquids that vaporize easily

nonvolatile

liquids that don’t vaporize easily

ex) motor oil at room temp

increase in surface area

increases both rate of vaporization and condensation so they cancel out→ vapor pressure doesn’t change

boiling point

• temperature which liquid’s vapor pressure equals external pressure

• when liquid reaches blank, the thermal energy is enough for molecules in interior of liquid to break free of their neighbors and enter gas state

sublimation

• transition from solid to gas

deposition

• gas to solid

melting point

0C

fusion

solid to liquid

melting

opposite of freezing

exothermic