5d Flashcards
is entropy a state function
yesssss
entropy is a function of
volume,, temp + number of moles of an ideal gas!!
in an ideal gas,, what does internal energy depend on
depends on temperature only
what is the driving force of chemical change
chemical potential
what does chemical potential do
it helps us predict the direction of a chemical reaction
what can internal energy be expressed as a function of
heat
work
change in molar of reactants aka how much there are.
the probability factor between change in molar amount and change in internal energy for a species called ‘i’ is
long u.
also known as chemical potential
dU = in terms of chem potential, temp and entropy , pressure and volume
TdS - pdV + u1 dN1 + u2 dN2
aka dU = TdS - pdV + (sum of chem potential of smt x by the number of molecules there are of it.)
okay so what does chemical potential depend on
depends on
S
V
Nk
aka chemical potential helpus us predict the direction of a chemical potential : so entropy, number of molecules or volume
dS in terms on internal and environment
dS = diS + deS.
whats dN in terms of i and e
dN = diN + deN
is mass exchanged in a closed system
nope
only energy
the entropy of an isolated system continues to increase bc of what
due to irreversible processed
diS > 0
U and V stays unchanged // constant
maximum entropy
- entropy of a system continues to increase if its an irreversible reaction bc diS > 0
when U and V stays unchanged
minimum energy
at constant entropy and volume
S and V
the system can reach minimum energy
max entropy needs what to be maximalised
max entropy needs
an isolated system
where diS > 0 occurs
where U and V are constant
min energy needs what to stay constant
it needs constant S and V
if smt is constant,, what would its d value be. aka if V is constant
dV = 0
dU in terms of T, S, p, V , diS
dU = TdS - pdV - TdiS
at constant T and V Helmholtz free energy in a closed system =
F = U -TS
at constant temp and volume,, in an irreversible process,, what would the value of F be
it would be at a minimum
what is gibbs energy // what does it correspond to
it corresponds to the max amount of energy available for doing work
implaying its a reversible reaction
what is the minimum gibbs energy
H -TS
if pressure and temperature are kept constant in a closed system
gibbs equals to H - TS but what else does it equal to
U + pV - TS
what is affinity
the extent of reaction + chemical potential
what is the symbol for chemical potential again
long u
when were talking about affinity in an equation,, aka the extent of reaction + chemical potential, what part is the chemical potential bit
the long u + long u - long u
where u do reactants - products
a non vanishing affinity means what
implies that a system is not at equilibrium
when can gibbs free energy be minimised
when pressure and temp is constant
in irreversible conditions
the extent of reaction (§) will reach §eq. where gibbs is at the minimum
think of a sloped curved line. with gibbs on the y axis and extent of reaction,§, on the x axis.
where u have §eq. aka the middle of the x axis,, this is where gibbs is lowest
-A = (dG/d§) p,T
to find out more about how maximalised entropy controls proccesses what do we need to look at
we need to look at calculating the mixing entropy of two different gases wwith the same number of moles,, N,, and we need to make sure that they occupy the same volume.
at constant temperature.
1 + 1 = 2 for the total volume
change in S mix when were trying to see how entropy maxing controls processes,, how do we find delta S mix
delta S mix = deltaS final - deltaS initial.
entropy of an ideal gas is affected by what
V
N
T
in equations,, what is Xk
mole fraction
Nk / N1 + N2
the number of microstates formed through the mixing process is equal to what:
W = (NaN1 + NaN2)! /
(Na N1)! (Na N2)!
delta S mix can also be found using what equation
the kb one
delta S mix = kB ln(Wmix)
R =
Na KB
ln( A/B) can also be found in what way
ln(a) - ln(b)
