Chem 124 Exam 1

Front 1

phase

Back 1

homogeneous part of th system in contact with other parts of the system but separated from them by a well defined boundary

Front 2

intermolecular forces

Back 2

attractive forces btw molecules

Front 3

intramolecular forces

Back 3

hold atoms together in a molecule

Front 4

van der Waals forces

Back 4

dipole-dipole, dipole induced dipole, and dispersion forces

Front 5

dipole dipole forces

Back 5

attractive forces btw polar molecules

Front 6

ion dipole forces

Back 6

attract an ion (either a cation or an anion) and a polar molecule to each other

Front 7

induced dipole

Back 7

separation of positive and negative charges in the atom (or nonpolar molecule) is due to the proximity of an ion or a polar molecule

Front 8

dispersion forces

Back 8

attractive forces that arise as a resule of temporary diples induced in atoms or molecules

Front 9

hydrogen bonding

Back 9

special type of dipole dipole interaction btw the hydrogen atom in a polar bond such as N-H, O-H, or F-H and an electronegative O,N,or F atom.

Front 10

surface tension

Back 10

amount of energy required to stretch or increase the surface of a liquid by a unit area

Front 11

cohesion

Back 11

intermolecular attraction btw like molecules

Front 12

adhesion

Back 12

attraction btw unline molecules

Front 13

viscosity

Back 13

measure of a fluid's resistance to flow

Front 14

solid

Back 14

possess rigid and long-range order; its atoms, molecules, orions occupy specific positions

Front 15

unit cell

Back 15

basic repeating structural unit of a crystalline solid

Front 16

coordination number

Back 16

number of atoms (or ions) surrounding an atom (or ion) in a crystal lattice

Front 17

closest packing

Back 17

most efficient arrangement of spheres

Front 18

X-ray diffraction

Back 18

scattering of X rays by the units of a crystalline solid

Front 19

amorphous solids

Back 19

lack a regular 3D arrangement of atoms

Front 20

glass

Back 20

rigid state without crystallizing

Front 21

phase changes

Back 21

transformations from one phase to another

Front 22

Evaporation or vaporization

Back 22

process in which a liquid is transformed into a gas

Front 23

condensation

Back 23

change from the gas phase to the liquid phase

Front 24

dynamic equilibrium

Back 24

rate of a forward process is exactly balanced by the rate of the reverse process

Front 25

equilibrium vapor pressure

Back 25

vapor pressure measured when a dynamic equilibrium exists btw condensation and evaporation

Front 26

molar heat of vaporization

Back 26

energy rquired to vaporize 1 mole of a liquid

Front 27

critical temperature

Back 27

above which its gas phase cannot be made to liquefy, no matter how great the applied pressure

Front 28

critical pressure

Back 28

minimum pressure that must be applied to bring about liquefaction at the critical temp

Front 29

melting point and freezing point

Back 29

temp at which solid and liquid phases coexist in equilibrium

Front 30

molar heat of fusion

Back 30

energy requierd to melt 1 mole of a solid

Front 31

supercooling

Back 31

liquid can be temporarily cooled to below its freezing point

Front 32

sublimation

Back 32

process in which molecules go directly from the solid into the vapor phase

Front 33

deposition

Back 33

molecules make the transition from vapor to solid directly

Front 34

molar heat of sublimation

Back 34

energy required to sublime 1 mole of a solid

Front 35

triple point

Back 35

only condition under which all 3 phases can be in equilibrium with one another

Front 36

saturated solution

Back 36

contains the max amount of a solute that will dissolve in a given solvent at a specific temp

Front 37

unsaturated solution

Back 37

contains less solute than it has the capacity to dissolve

Front 38

supersaturated solution

Back 38

contains more solute than is present in a saturated solution

Front 39

solvation

Back 39

process in which an ion or molecule is surrounded by solvent molecules arranged ina specific manner

Front 40

percent by mass

Back 40

ratio of the mass of a solute to the mass of the solution X 100

Front 41

molality

Back 41

number of moles of solute dissolved in 1kg of solvent

Front 42

fractional crystallization

Back 42

separation of a mixture of substances into pure components on the basis of their differing solubilities

Front 43

colligative properties

Back 43

properties that depend only on the # of solute particles in solution and not on the nature of the solute particles

Front 44

nonvolatile

Back 44

does not have a measurable vapor pressure

Front 45

Raoult's law

Back 45

the vapor pressure of a solvent over a solution is given by the vapor pressure of the pure solvent, times the mole fraction of the solvent in the solution

p(l)=X(l)P(l)

Front 46

volatile

Back 46

have measurable vapor pressure

Front 47

fractional distillation

Back 47

procedure for separating liquid components of a solution based on their different boiling points

Front 48

boiling point elevation

Back 48

boiling point of the solution minues the boiling point of the pure solvent

Front 49

freezing point depression

Back 49

freezing point of the pure solvent minus the freezing point of the solution

Front 50

osmosis

Back 50

selective passage of solvent molecules through a porous membrane froma dilute solution to a more concentrated one

Front 51

semipermeable membrane

Back 51

allows the passage of solvent molecules but blocks the passage of solute molecules

Front 52

osmotic pressure

Back 52

pressure required to stop osmosis

Front 53

van't Hoff factor

Back 53

i= actual # of particles in solution after dissciation/ # of formula units initially dissolved in solution

Front 54

ion pair

Back 54

one or more cations and one or more anions held together by electrstatic forces

Front 55

colloid

Back 55

dispersion of particles of one substance throughout a dispersing medium made of another substance

Front 56

hydrophilic

Back 56

water loving

Front 57

hydrophobic

Back 57

water hating