lecture 10

Question 1

when is equilibrium reached

Answer 1

when the rates of forward and backward reactions are equal

Question 2

A <=> B
if we allow the reaction to proceed from left to right,, how can we measure the change

Answer 2

we can measure the change with a variable {
‘extent of reaction’

Question 3

what is { and what is it used to measure

Answer 3

extent of reaction
measures the change that occurred from the reaction taking place (for a certain amount of time)

Question 4

A <=> B
change in Bs moles (nb) is what in terms of extent of reaction, {

Answer 4

dnB = d{

Question 5

A <=> B

change in moles of A in terms of extent of reaction

Answer 5

dnA = -d{

bc it’s going from A to B meaning the amount of A moles with decrease.

Question 6

what does dG/d{ equal

Answer 6

uB-uA

=

🔺G reaction

Question 7

what does enthalpy change tell us about

Answer 7

tells us about surroundings entropy
🔺H —> Ssurr

Question 8

what mixing tell us about

Answer 8

Ssystem

system entropy

Question 9

the gibbs energy change associated with a reaction changes with pressure bc whattttt

Answer 9

RTln(pB/pA)

Question 10

bc the ratio of partial pressures defines the change in gibbs energy,, it is given a specific name

Answer 10

reaction quotient Q : pB/pA

Question 11

what is Q

Answer 11

reaction quotient
pB/pA

defines gibbs energy

Question 12

gibbs energy using reaction quotient

Answer 12

G = G* + RTln(Q)

Question 13

at equilibrium what occurs

Answer 13

G = 0
reaction quotient (Q) = equilibrium constant (K)

so G/0 (bc at equilibrium) = G* + RTln(K)

Question 14

what does K equal if equation : 0 = G + RTln(K) is rearranged

Answer 14

e(-G*/RT) = K

Question 15

is G is positive it isss

Answer 15

endergonic at standard conditions

PA > PB at equilibrium

Question 16

if G is negative it issss

Answer 16

exergonic at standard conditions

pB>pA at equilibrium

Question 17

how else can G be found

Answer 17

sum of
(chem potential x stoichiometric factor ) d{

Question 18

how else can G be foundddd

Answer 18

sum of standard chemical potentials x stoichiometric factors

+ RT sum of stoichiometric factor x ln(p/ p*)

p* is standard pressure

Question 19

what does pA/p* equal to in an ideal gas

Answer 19

it equals to aA

the activity of A

Question 20

how can we show that K is related to partial pressures of the species at equilibrium if we assume the gases are equal

Answer 20

K = a^ x products / a ^ x reactants

x = stoichiometry

Question 21

if pA/p* is aA how can the reaction coefficient equation, Q be written

Answer 21

Q = aC^c. aD^d // aA^a aB^b

Question 22

what is the activity, aX, for X if X is a pure solid

Answer 22

1

Question 23

what is the activity at standard conditions

Answer 23

1

Question 24

when does equilibrium occur

Answer 24

when gibbs free energy is minimised
molar gibbs on LHS = molar gibbs on RHS

Question 25

at equilibrium,; what’s the value of G

Answer 25

0

Question 26

at equilibrium,, what does ln(Q) equal to

Answer 26

ln(K)

equilibrium constant