DAT Gen Chem Thermodynamics and Thermochemistry Flashcards
that energy cannot be created or destroyed. what law
first law of thermodynamics, or law of conservation of energy
the chemical reaction
containing reactants and products
systhem
the environment that
surrounds the system
surroundings
the sum of the system and
its surroundings
universe
heat being
transferred from the surroundings into the
system, making the change in enthalpy for the
system greater than 0 (∆H > 0).
endothermic
heat being transferred from the system to the
surroundings, making the change in enthalpy
for the system less than 0 (∆H < 0)
exothermic
amount of heat
energy contained within a system.
enthalpy
endothermic phase changes
sublimation, vaporization, melting
exothermic phase changes
deposition, condensation, freezing
transfer of heat via direct
contact.
conduction
exist in
liquids or gases when hotter, less dense
areas rise, and the cooler, more dense areas
sink.
convection
transfer of heat via
electromagnetic…
radiation
change in internal energy =
heat + work
work =
- Pressure x change in volume
When there is an increase in volume (ΔV > 0),
work is WHAT the system.
done by, negative work
positive q value
endothermic
negative q value
exothermic
positive work value
compression
negative work value
expansion
defined by the
amount of energy required to raise the
temperature of 1.0 gram of a substance by
1°Celsius.
specific heat capacity
the specific heat
capacity for the same molecule differs
depending on…
the molecular state
(no phase change) heat absorbed or released by substance =
mass x specific heat capacity x delta T
(phase change) heat absorbed or released by substance =
mass of substance (kg) x heat of fusion/vap
heat required to change a
substance from liquid to gas.
heat of vaporization
heat required to change a substance from solid
to liquid.
heat of fusion
heat of reaction =
- heat of calorimeter
heat of calorimeter =
heat capacity of calorimeter x change in temp
a property that
depends only on the initial and final state of the
system, and is independent of the path taken.
state function
describes the amount of disorder/
randomness of a system.
entropy
what kind of reaction is favored
exothermic
which is more stable, hi entropy or low
high
states that
the entropy of the universe is always increasing.
second law of thermodynamics
states that
the entropy of a pure crystalline substance at
absolute zero temperature (0 Kelvin) is zero.
third law of thermodynamics
∆Srxn > 0 - reaction is
entropically favorable;
products are more disordered than the
reactants.
as dissolution increases, what happens to entropy
increases
criteria for
spontaneity, and it depends on entropy (∆S),
enthalpy (∆H), and temperature.
Gibbs Free Energy (∆G)
delt g =
delt h - (temp x delt s)
∆G < 0
spontaneous rxn
∆G > 0
nonspontaneous
if delt g is negative, what is k value
above 1
if delt g is positive, what is k value
less than one
