mcat chemistry chapter 6 thermochemistry kaplan

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a spontaneous react may or may not?: proceed to completion
system: partic part of universe being studied
enviroment: everthing outside system
system can be?: isolated
closed
open
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: process
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: adiabatic
which 2 processess are common?: isothermal and isobaric. temp and ress are easy to contr
T or F heat and temp are different: t
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: temperature
heat is a form of e that transfers bec of?: a temper diff betw syst and its surroundings
heat absorbed by a system is?: pos
heat lost by a system to surrounding is?: negative
endothermic react?: absorb e
exothermic react?: release e
units of heat?: joules
1 cal = ________ J: 4.184 J
joules and calories are units for?: heat
calorimetry measures?: heat changes
what condit are heat changed measured under?: const vol calorimetry
const press calorimetry
heat absorbed or given off in a process is =?: q=mc chT
q=mc chT c is?: specific heat
q=mc chT q is?: heat
const vol calorimetry what dev do you use?: bomb calorimeter
bomb calorimeter no ____________ enters or leaves the system: heat
q react + q water + q steel=0 in a ?: bomb calorimeter
bomb calorimeter, the overall system is?: adiabatic
macroscopic prop include?: temp T
press P
volume V
state functions: prop that dep only on initial and final states of the system
name 7 state funct?: temp
vol
enthalpy
entropy
free energy
internal energy E and U
H is?: enthalpy
s is: entropy
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
enthalpy is?: heat changes at constant pressure
enthalpy of a process does not depend on the?: path
T or F Î”Hreact=Hprod-Hreact: T
T or F it is not poss to meas H directly: T
only ____________ in H can be measured: Î”
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
Î”Hf of an element in its standard state is?: zero
standard heat of react is?: Î”Hreact= (sum of Î”Hf of prod)-(sum of Î”Hf 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 Î”H?: 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: breakage
bond ______________ is always exothermic: formation
H2 (g) ---> 2H (g) Î”H= will be?: positive
bond e can be used to estim the ?: enthalpies of reactions
Î”Hreact can be estimated by?: =(Î”H of bonds broken)- (Î”H 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 Î”H?: that react be fast and spontan
entropy is the meas of?: disorder of a system
what are units of entropy?: j/K
J/K are the units for ?: entropy
a solid has a lower entropy than a ?: gas
t or f entropy is a state function: T
Î”S=Sfin- Sinit: Sfin- Sinit
qrev/T =: Î”S
Î”S= ?/T: qrev/T
entropy qrev is ?: the heat added to the syst undergoing a rever process.
freezing has a ___________ in entropy: decrease
boiling has a ____________ in entropy: increase
second law of thermodyn says that?: all spont proceed so that entropy of the systm plus its surr increases
Î”Suniv >: 0
a sytm reaches its maxim entropy at?: equilibrium
for a revers procc Î”Suniv is?: zero
Gibbs free energy combines what 2 fact?: Î”H and Î”S
Goose hunters take shotguns reminds you of?: Î”G=Î”H-TÎ”S
Î”G=?: Î”G=Î”H-TÎ”S
in the equilbr state, free e is?: at a minimum
Î”G <0 means a proc can?: occur spont
for any given nonspont react or proc, the reverse react or proc will be?: sponaneous
if Î”G is zero the system is?: in a state of equil
thermody and kinetics spontan does not necessaril mean?: instantaneous
Î”H Î”S Outcome ? - +: spontaneous at all temperatures
Î”H Î”S + -: nonspontaneous at all temperatures
Î”H Î”S + +: spontaneous only at high temperatures
Î”H Î”S - -: spontaneous only at low temperatures
rate of a reac depends on?: activat e
t or f rate of a react dep on Î”G: f
standard free energy Î”G is ?: Î”G 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?: zero
conversion of C (diamond) to C (graphite) is __________ but its rate is slow: spont
Î”G react=(sum of Î”Gf of prod)- ??: =(sum of Î”Gf of prod)- (sum of =(sum of Î”Gf of react)
-RTlnKeq =: Î”G
what is the equat for Î”G from equil const?: Î”G=-RTlnKeq
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=: Q=[C]^c[D]^d/[A]^a[B]^b
when a react commences Î”G=?: Î”G= Î”GÂ° + RTlnQ
discuss when water boils in terms of ch in G: TchS> chH only when T is above 373 K

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