mcat chemistry chapter 6 thermochemistry kaplan Flashcards

Terms Definitions
a spontaneous react may or may not?
proceed to completion
partic part of universe being studied
everthing outside system
system can be?
isolated system can?
it can not exch e or matter with surroundings
give an ex of an isolated system?
insulated bomb reactor
closed system is?
can exch e but not matter
ex of a closed syst
steam radiator
open system is?
can exch matter and e with surroundings.
give example of an open syst?
pot of a boiling water
a system undergoes a ____________ when one or more of its properties change
a system undergoes a process when?
when one or more of its prop change
isothermal process is?
temperat of systm is const
adiabatic proc is when?
no heat exch occurs
isobaric process is?
press of systm is const
no heat exch occurs in a __________ process
which 2 processess are common?
isothermal and isobaric. temp and ress are easy to contr
T or Fheat and temp are different
heat is a?
form of energy that can leave or enter a syst
temp is?
a measure of average ke of particles in a systm
____________ is a meas of the averag ke of the particles in a syst
heat is a form of e that transfers bec of?
a temper diff betw syst and its surroundings
heat absorbed by a system is?
heat lost by a system to surrounding is?
endothermic react?
absorb e
exothermic react?
release e
units of heat?
1 cal = ________ J
4.184 J
joules and calories are units for?
calorimetry measures?
heat changes
what condit are heat changed measured under?
const vol calorimetryconst press calorimetry
heat absorbed or given off in a process is =?
q=mc chT
q=mc chTc is?
specific heat
q=mc chTq is?
const vol calorimetrywhat dev do you use?
bomb calorimeter
bomb calorimeterno ____________ enters or leaves the system
q react + q water + q steel=0 in a ?
bomb calorimeter
bomb calorimeter, the overall system is?
macroscopic prop include?
temp Tpress Pvolume V
state functions
prop that dep only on initial and final states of the system
name 7 state funct?
tempvolenthalpyentropyfree energyinternal energy E and U
H is?
s is
G is ?
free energy
E or U is?
internal energy
standard condition for enthalpy etc is?
25 C, 1 atm
standard state of a subs is the form a subst takes?
at 25 C and 1 ATM
standard condit in thermody must not be confused with?
standard temperature and pressure in gas laws STP
heat changes at const press, is
enthalpy is?
heat changes at constant pressure
enthalpy of a process does not depend on the?
T or FΔHreact=Hprod-Hreact
T or Fit is not poss to meas H directly
only ____________ in H can be measured
stand heat of format of a compound is?
enthalpy ch that would occur if one mole of a comp were formed direct from its elem in their standard states
ΔHf of an element in its standard state is?
standard heat of react is?
ΔHreact= (sum of ΔHf of prod)-(sum of ΔHf of react)
Hess law says?
that enthalpies of react are additive
for hesses law, if you multiply the prod and react by 3 ( or a cert number) then what must you do to ΔH?
also multiply it by 3
reverse reaction has the same __________ as that of the forward react, but its ________ is oppos
enthalpy,but its sign is oppos
bond e or bond dissoc e is?
averag of the energy req to break a part type of bond in one mole of gaseous molec
bond ____________ is always endothermic
bond ______________ is always exothermic
H2 (g) ---> 2H (g) ΔH= will be?
bond e can be used to estim the ?
enthalpies of reactions
ΔHreact can be estimated by?
=(ΔH of bonds broken)- (ΔH of bonds formed)
for simple diatomic molec such as H2, bond dissoc e can be easily measured?
spectroscopically using react E=hv E=bond dissoc e and v is freq of light absorbed
spectroscopy can be used to measure the bond dissoc e of?
simple diatomic molecules
what are the req for relatively easy measure of ΔH?
that react be fast and spontan
entropy is the meas of?
disorder of a system
what are units of entropy?
J/K are the units for ?
a solid has a lower entropy than a ?
t or fentropy is a state function
ΔS=Sfin- Sinit
Sfin- Sinit
qrev/T =
ΔS= ?/T
entropyqrev is ?
the heat added to the syst undergoing a rever process.
freezing has a ___________ in entropy
boiling has a ____________ in entropy
second law of thermodyn says that?
all spont proceed so that entropy of the systm plus its surr increases
ΔSuniv >
a sytm reaches its maxim entropy at?
for a revers procc ΔSuniv is?
Gibbs free energy combines what 2 fact?
ΔH and ΔS
Goose hunters take shotguns reminds you of?
in the equilbr state, free e is?
at a minimum
ΔG <0 means a proc can?
occur spont
for any given nonspont react or proc, the reverse react or proc will be?
if ΔG is zerothe system is?
in a state of equil
thermody and kineticsspontan does not necessaril mean?
ΔH ΔS Outcome ?- +
spontaneous at all temperatures
ΔH ΔS + -
nonspontaneous at all temperatures
ΔH ΔS + +
spontaneous only at high temperatures
ΔH ΔS - -
spontaneous only at low temperatures
rate of a reac depends on?
activat e
t or frate of a react dep on ΔG
standard free energy ΔG is ?
ΔG of a proc occur at 25 C and 1 atm . concentr of sol are 1 M
standard free energy of format of a comp is?
free energy ch that ocurs when 1 mol of a comp in its stand form
standard free energy of format of any elem in its most stable form is?
conversion of C (diamond) to C (graphite) is __________ but its rate is slow
ΔG react=(sum of ΔGf of prod)- ??
=(sum of ΔGf of prod)- (sum of =(sum of ΔGf of react)
-RTlnKeq =
what is the equat for ΔG from equil const?
once a react commences a standard state condit?
no longer holds
once a react commences Keq must be replac by?
reaction quotient Q
the react quotient Q is=
when a react commences ΔG=?
ΔG= ΔG° + RTlnQ
discuss when water boils in terms of ch in G
TchS> chH only when T is above 373 K
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