UARK Chem 2 Exam 1

solid phase

strong intermolecular forces, definite shape/volume

liquid phase

some intermolecular forces overcome by thermal energy, indefinite shape/definite volume

gas phase

intermolecular forces have been completely overcome by thermal energy, indefinite shape/volume

crystalline solids

regular ordered structures (salt, ice, sugar)

amorphous solids

no long range order (glass, wax, plastic)

intermolecular forces occur

between molecules

bonds occur

within a molecule

bonds are _____ than intermolecular forces

stronger

dispersion forces

weakest, between nonpolar molecules

dipole dipole forces

occur between molecules with permanent dipole, polar

hydrogen bonding

strongest intermolecular force in a pure substance, must bond with oxygen, nitrogen, or fluorine

ion dipole force

ionic solids dissolved into water, polar, even stronger

dispersion forces are the result of

instantaneous dipole interacting with an induced dipole

dispersion forces are present between

all molecules and atoms but only force between nonpolar molecules

induced dipole causes an attraction between

2 helium atoms

intermolecular forces increase as

boiling point, surface tension, viscosity, and melting point increase

intermolecular forces increase as

vapor pressure decreases

dispersion forces are weak in

noble gases

dispersion forces increase with

increasing molar mass

larger atoms are

more polarizable (outer electrons not held as tightly)

larger atoms have

higher boiling points

miscibility

ability of two liquids to be mixed without separating

like dissolves

like (polar/polar) (nonpolar/nonpolar)

which intermolecular force can overcome electrostatic forces keeping ions in a crystal lattice

ion dipole forces

hydrogen bonding is weaker than

covalent and ionic bonding

surface tension

tendency of liquids to minimize their surface area

surface tension of a liquid

the energy required to increase the surface area by a unit amount

viscosity

resistance of a liquid to flow

viscosity decreases with

increasing temperature

capillary action

the ability of a liquid to flow against gravity up a narrow tube

cohesive forces

the attraction between molecules in a liquid

adhesive forces

the attraction between liquid molecules on the surface of the tube

___ forces draw and liquid around the edge of the tube up the walls

adhesive

the water in the rest of the column is pulled along by ___ forces

cohesive

vaporization

process by which thermal energy can overcome intermolecular forces and produce a state change from liquid to gas

rate of vaporization increases with

increasing temperature and surface area but decreasing intermolecular force strength

volatile

liquids that vaporize easily (weak intermolecular forces)

nonvolatile

liquids that do not vaporize easily (stronger intermolecular forces)

vaporization is

endothermic

enthalpy of vaporization

the heat required to vaporize one mol of a liquid to gas, increases with increasing intermolecular forces

condensation

going from gas to liquid, exothermic (releasing heat)

dynamic equilibrium is reached when

rate of condensation and vaporization are equal

vapor pressure

the pressure of a gas in dynamic equilibrium with its liquid

when a system in dynamic equilibrium is disturbed

the system responds as to minimize the distance and return to a state of equilibrium

boiling point

the temperature at which the liquid's vapor pressure equals the external pressure

normal boiling point of a liquid

the temperature at which the vapor pressure equals 1 atm

once the boiling point of a liquid is reached does it raise the temperature of the liquid above its boiling point?

no, additional heating only causes more rapid boiling

supercritical fluid

neither liquid nor gas

critical temperature

the temperature at which the transition to a supercritical fluid occurs

critical pressure

the pressure at which the transition occurs

sublimation

the transition from solid directly to gas (dry ice at room temperature)

deposition

the transition from gas directly to solid

melting/fusion

the transition from solid to liquid

freezing

the transition from liquid to solid

enthalpy of fusion

the heat required to melt 1 mole of a solid

enthalpy of fusion increases with

increasing intermolecular forces

fusion is ____ because melting is _____

positive, endothermic

triple point

represents the temperature and pressure above which a supercritical fluid exists

what favors the more dense state?

increasing pressure

if the fusion curve has a positive slope

the solid state is more dense

if the fusion curve has a negative slope

the liquid state is more dense

solubility

the amount of solute that will dissolve in a given amount of solvent

entropy

a measure of energy randomization or energy dispersal in a system

when gases mix, entropy ___

increases

solvent solute interactions are greater than or equal to solvent solvent and solute solute interactions

solution generally forms

solvent solute interactions are less than solvent solvent and solute solute interactions

solution may or may not form, depending on relative disparity

miscible

when two liquids form a homogenous solution in all proportions

enthalpy of solution

the overall enthalpy change of solution formation

heat of hydration

the energy change that occurs when 1 mole of the gaseous solute ions are dissolved in water

saturated solution

has exactly the maximum amount of solute that can be dissolved in the solvent

unsaturated solution

has less than the maximum amount of solute that can be dissolved in the solvent

supersaturated solution

has more than the maximum amount of solute that can be dissolved in the solvent

in gases, as solubility increases

pressure increases

in gases, as solubility decreases

temperature increases

what solutions have water as the solvent?

aqueous solutions

molecular solids

have low melting points and the repeating unit in the crystal structure is the molecule (dry ice)

network covalent solids

have high melting points and are held together by covalent bonds (graphite)

ionic solids

have high melting points and are held together by electrostatic interactions (barium chloride)

is it possible to have a solution where the solvent and solute are both in the gas phase?

yes

the spontaneous mixing of two ideal gases when a barrier is removed causes an

increase in entropy

atomic solids

composite units are atoms

nonbonding solids

held together by dispersion forces, low melting points (solid xenon)

metallic solids

held together by metallic bonds, variable melting points (gold)