lecture 10 Flashcards
when is equilibrium reached
when the rates of forward and backward reactions are equal
A <=> B
if we allow the reaction to proceed from left to right,, how can we measure the change
we can measure the change with a variable {
‘extent of reaction’
what is { and what is it used to measure
extent of reaction
measures the change that occurred from the reaction taking place (for a certain amount of time)
A <=> B
change in Bs moles (nb) is what in terms of extent of reaction, {
dnB = d{
A <=> B
change in moles of A in terms of extent of reaction
dnA = -d{
bc it’s going from A to B meaning the amount of A moles with decrease.
what does dG/d{ equal
uB-uA
=
🔺G reaction
what does enthalpy change tell us about
tells us about surroundings entropy
🔺H —> Ssurr
what mixing tell us about
Ssystem
system entropy
the gibbs energy change associated with a reaction changes with pressure bc whattttt
RTln(pB/pA)
bc the ratio of partial pressures defines the change in gibbs energy,, it is given a specific name
reaction quotient Q : pB/pA
what is Q
reaction quotient
pB/pA
defines gibbs energy
gibbs energy using reaction quotient
G = G* + RTln(Q)
at equilibrium what occurs
G = 0
reaction quotient (Q) = equilibrium constant (K)
so G/0 (bc at equilibrium) = G* + RTln(K)
what does K equal if equation : 0 = G + RTln(K) is rearranged
e(-G*/RT) = K
is G is positive it isss
endergonic at standard conditions
PA > PB at equilibrium
if G is negative it issss
exergonic at standard conditions
pB>pA at equilibrium
how else can G be found
sum of
(chem potential x stoichiometric factor ) d{
how else can G be foundddd
sum of standard chemical potentials x stoichiometric factors
+ RT sum of stoichiometric factor x ln(p/ p*)
p* is standard pressure
what does pA/p* equal to in an ideal gas
it equals to aA
the activity of A
how can we show that K is related to partial pressures of the species at equilibrium if we assume the gases are equal
K = a^ x products / a ^ x reactants
x = stoichiometry
if pA/p* is aA how can the reaction coefficient equation, Q be written
Q = aC^c. aD^d // aA^a aB^b
what is the activity, aX, for X if X is a pure solid
1
what is the activity at standard conditions
1
when does equilibrium occur
when gibbs free energy is minimised
molar gibbs on LHS = molar gibbs on RHS
at equilibrium,; what’s the value of G
0
at equilibrium,, what does ln(Q) equal to
ln(K)
equilibrium constant
