Unit 4: IMFs & Thermodynamics Flashcards
forces between particles (atoms, molecules, or ions) of a substance are called ________________
intermolecular forces
bonds within molecules or formula units are called __________________
intramolecular forces
the dominant forces between molecules are _____________
electrostatic
dispersion forces are __________ and _____________ attractive forces between _____________ dipoles
very weak, very short range, temporary (induced)
dispersion forces are the only forces between ___________ molecules
nonpolar
dispersion forces are also called
London forces, van der Waals, or induced dipoles
dispersion forces are __________ rather than ______________ dipole-dipole interactions
temporary; permanent
polarizability ___________ with increasing numbers of electrons and, therefore, with increasing sizes of molecules
increases
London forces are generally ____________ for molecules that are larger or have more electrons
stronger
IMF result from attractive forces between regions of ____________ and ____________ charge density in neighboring molecules
positive, negative
_________ interactions are so strong, they can even be considered intermolecular forces as well as intramolecular forces
ionic
surface tension describes the inward forces that must be overcome in order to ________ the surface area of a liquid
expand
viscosity increases as IMFs __________ in strength and as the temperature __________
increase; decreases
the vapor pressure of all liquids ___________ with temperature
increases
at room temperature, a liquid with ______ vapor pressure is called volatile
high
diamond is a __________ crystal of carbon
covalent
diamond and graphite are two _____________ forms of carbon
crystalline
graphite forms __________ while diamond is ______________
flat sheets; tetrahedral
the electrons in metallic solids are _____________
delocalized to form a “sea of electrons” that allow electricity (the movement of electrons) to flow freely
First Law of Thermodynamics: During any physical or chemical change, the total amount of energy in the universe is __________
conserved (Law of Conservation of Energy)
Total energy = __________ + ____________
kinetic energy, potential energy
Total energy = __________ = ___________ + ___________
internal energy, heat energy, work energy
State functions are a property of the system whose value depends ONLY on the __________ and ___________ states of system
initial, current
(symbols are capital letters)
usually the reaction: the reactants and products
system
the rest: the beaker, the air in the room, etc
surroundings
system + surroundings
universe
open system
exchange energy & matter
closed system
exchange energy only
isolated system
no exchange of energy or matter
isothermal
constant temperature
adiabatic
constant heat
isobaric
constant pressure
Internal energy is the sum of the _________ and ___________ energy of all _________ in the system
kinetic
potential
particles
endothermic reaction:
sign for q:
absorbing heat, q > 0
exothermic reaction:
sign for q:
gives off heat, q < 0
positive work is work done __ system __ surroundings
volume is __________
on, by, decreasing
negative work is work done __ system __ surroundings
volume is ___________
by, on, increasing
specific heat is how much _________ is required to heat ____________ of a substance by one degree
heat, one gram
heat of fusion is how much heat is required ________ __________ of a substance without changing the ___________
to melt one gram, temperature
heat of vaporization is how much heat is required to __________ ________ of a substance without changing the ____________
vaporize one gram, temperature
sublimation
solid to gas
deposition
gas to solid
unit for heat of vaporization
J/g
___________ is heat at constant pressure
enthalpy change (∆H)
heat of combustion is the _________ change for the combustion reaction in which _____ mole of the fuel is reacted
enthalpy, one
calorimetry
an experimental technique to measure the energy change associated with a chemical or a physical process
bomb calorimeter = constant ___________
volume
coffee cup calorimeter = constant _____________
pressure
standard ________ enthalpies of formation is enthalpy for reaction in which ____________ of a substance in a specified state is formed from its constituent elements in their ___________
molar, one mole, standard states
larger atoms and molecules are more __________ than smaller atoms and molecules
polarizable
__________ IMFs = most ideal gas
weaker
the stronger the IMFs, the ________ the vapor pressure
weaker
_________ IMFs = more viscosity
stronger
nonmetals that melt below 500K are __________ solids
molecular
nonmetals that melt above 500K are _________ solids
covalent
breaking bonds ______ energy
absorbs
forming bonds _______ energy
gives off
ion-ion forces have a full and __________ charge
permanent
hydrogen bonding has a partial and __________ charge
permanent
third law of thermodynamics: the entropy of a ____________, _________________ substance at ____________ is zero
pure, perfect crystalline, absolute zero
Gibbs Free Energy will always be ________ for spontaneous processes
negative
when free energy is greater than zero, it is ______ stable
less
when free energy is less than zero, it is _______ stable
more
in a combustion reaction, heat is always ___________
released
condensation
gas to liquid
vaporization
liquid or solid to gas
evaporation
liquid to gas
for a given reaction, if ∆H (enthalpy change of the reaction) is _____________ and ∆S (entropy change) is ___________, then the value of ∆G (free energy) will ALWAYS BE NEGATIVE
negative, positive
_________ law of thermodynamics: all _____________ changes are accompanied by an ___________ in universal entropy
second, spontaneous, increase
reactions that occur spontaneously in one direction cannot occur spontaneously in the ___________ direction
reverse
non-spontaneous means that entropy change is __________
negative
entropy is a _____________ function that is a measure of the ____________ of energy
state, dispersal
elements in their ____________ states will have change of free energy (∆G) equal to ___________
standard, zero
third law of thermodynamics
the entropy of a pure, perfect crystalline substance at absolute zero is zero
first law of thermodynamics (law of conservation of energy)
during any physical or chemical change, the total amount of energy in the universe is conserved
standard states
how elements exist when they are at 1 atm pressure and 25 degrees Celsius
molar heat of formation
the enthalpy change for the formation of one mole of product from its elements in their standard states
the change in internal energy, ∆U, for a process is equal to the amount of heat __________ at constant ____________
absorbed, volume
the change in enthalpy, ∆H, for a process is equal to the amount of heat ____________ or _____________ at constant __________
absorbed, released, pressure
for a _____________ change, a positive change in entropy for the system is matched by a negative entropy change for the surroundings
physical
