Chem 102 First exam

intramolecular

between 2 atoms

intermolecular

between 2 molecules

intermolecular forces

boiling point, melting point, viscosity, surface tension, and capillary action

Which one is stronger between chemical bonds and intermolecular forces?

chemical bonds

weakest to stronger intermolecular forces

LDF (in everything), dipole-dipole, hydrogen

polarizability

tendency of an electron cloud to distort

Dispersion forces

non polar particle can be temporarily polarized to create this force

Polarizability increases …

as number of electrons increase

factors that affect amount of dispersion force

number of electrons in an atom, size of atom or molecule/molecular weight, and shape of molecules (more compact, less dispersion)

Dipole

Polar molecules have a more positive and negative end

Dipole-dipole interactions

the oppositely charged ends attract each other

boiling point is higher when

the molecule is more polar (molecules of the same mass and size)

If two molecules are of comparable size and shape (what is the greater force)

dipole-dipole interactions will likely be the dominating force

If one molecule is much larger than another (what is the greater force)

dispersion forces will likely determine its physical properties

Hydrogen bonding

attraction between a hydrogen atom attached to a highly electronegative atom and a nearby small electronegative atom in another molecule or chemical group

What atoms does hydrogen bond to to form a hydrogen bond?

N,O, or F

Hydrogen bonds arise in part from …

high electronegativity of nitrogen, oxygen, and fluorine

hydrogen bonding makes the molecules _______ in ice than in liquid water

farther apart

Ion-dipole interactions

exist between an ion and a polar molecule (ex. NaCl in water)

viscosity

resistance of a liquid to fliw

Viscosity increases with stronger intermolecular forces and _______ with higher temperature

decreases

viscosity tips

long molecules can become tangled easier and viscosity increases with molecular weight

cohesive forces

intermolecular forces that bind similar molecules to one another

adhesive forces

intermolecular forces that bind a substance to a surface

capillary action

rise of liquids up narrow tubes

phase change

conversion from one state of matter to another (energy is added or released)

another name for melting

fusion

heat of fusion

the energy required to change a solid at its melting point to a liquid

heat of vaporization

the energy required to change a liquid at its boiling point to a gas

heat of sublimation

the energy required to change a solid directly to a gas

“vertical” areas (heat curves graph)

q=m(change T)(Cspecific)

Horizontal areas (heating curves graph)

q=mol(change H)

Vapor pressure

as temperature rises, vapor pressure increases

As more molecules escape the liquid, the pressure

increases

liquid molecules evaporate and vapor molecules condense at ______

the same rate

boiling point of a liquid is the temperature at which its vapor pressure _______ atmospheric pressure

equals

normal boiling point is the temperature at which its vapor pressure is _______

760 torr

phase diagram

a graph showing a mater under conditions of temperature and pressure

normal phase diagram

phase diagram of water

phase diagram of carbon dioxide

critical temperature

The temperature beyond which a gas cannot be compressed

critical pressure

The pressure needed to compress the liquid at critical temperature

greater IMF =

higher critical temperature and pressure

liquid crystal

intermediate state, liquid crystals have structure of a solids and free motion of liquid

Metallic solids

held together by a “sea” of collectively shared electrons

Ionic solids

sets of cations and anions mutually attracted to one another

Covalent-network solids

joined by an extensive network of covalent bonds

Molecular solids

discrete molecules help together by weak forces

Metallic bonding

metal ion and sea of mobile valence electrons

crystalline

solids with a regular repeating pattern of atoms

amorphous solids

characterized by a distinct lack of order in arrangement of atoms

solutions

homogeneous mixtures of two or more pure substances

solvent

present in the largest amount

solutes

the other components in solutions

ability of substances to form solutions depends on:

natural tendency toward mixing and intermolecular forces

entropy

amount of disorder in a system

mixing of gases is a ______ process

spontaneous

Mixing causes ______ randomness in the position of molecules

more

The formation of solutions is favored by the ______ in entropy that accompanies mixing

increase

solute-solute interactions (when forming a solution)

must be overcome to disperse these particles when making a solution

solvent-solvent interactions (when forming a solution)

must be overcome to make room for the solute

solvent-solute interactions (when forming a solution)

occur as the particles mix

solution-making process and _______ are opposing forces

crystallization

dynamic equilibrium

occurs when the rate of the opposing processes is equal

saturated solution

additional solute will not dissolve unless some crystallizes from solution

unsaturated solution

not yet reached the amount that will result in crystallization

solubility

the maximum amount of solute that can dissolve in a given amount of solvent at a given temperature

supersaturated

the solvent holds more solute than is normally possible at that temperature

factors that affect solubility

solute-solvent interactions, pressure (for gaseous solutes), and temperature

The stronger the solute-solvent interaction, the _________ the solubility of a solute in that solvent

greater

polar organic molecules dissolve in water ______ than non polar organic molecules

better

miscible

liquid that mix in all proportions

immiscible

liquids that do not mic in one another

Pressure effects

the solubility of solids and liquids are not appreciably affected by pressure

gas solubility _______ affected by pressure

is

as gas pressure above the solvent increases, solubility _______

increases

The solubility of most solid solutes in water ______ as the solution temperature increases

increases

The solubility of gases in water ________ with increasing temperature

decreases

quantitative =

numbery

qualitative =

feely

mass %

(mass of component in solution/total mass of solution) x 100%

ppm of component

(mass of component in solution/total mass of solution) x 10^6

ppb of component

(mass of component in solution/total mass of solution) x 10^9

Mole fraction

x = (mol of component/total mol of all components)

Molarity (M)

mol of solute/L of solution

Molality (m)

mol of solute/kg of solvent

Colligative properties depend only on

the quantity, not on the identity of the solute particle

colligative properties include:

vapor-pressure lowering, boiling-point elevation, freezing-point depression, and osmotic pressure

volatile solution

has vapor pressure

nonvolatile solution

no measurable vapor pressure

solute-solvent intermolecular attraction between nonvolatile solutes and volatile solvent makes it _____ for solvent to escape to the vapor phase

harder

Boiling-point elevation

since vapor pressures are lowered for solutions, it requires a higher temperature to reach atmospheric pressure (boiling point is raised)

Freezing point depression

The construction of the phase diagram for a solution demonstrates that the freezing point is lowered while the boiling point is raised.

boiling-point elevation (equation)

(change T) = T(solution)-T(solvent) = iKm

freezing-point depression

(change T) = T(solution)-T(solvent) = -iKm

osmosis

the net movement of solvent molecules from solution of low to high concentration of solute across a semipermeable membrane

osmotic pressure

I(n/v)RT = iMRT

isotonic solutions

same osmotic pressure; solvent passes the membrane at the same rate both ways

hypertonic solution

lower osmotic pressure; solvent will leave this solution at a higher rate than it enters with