3e

Question 1

gibbs adsorption isotherm equation =

Answer 1

gamma = -1/nrt. d§/dln(c)

gives us surface excess aka conc of SF on the interface.

Question 2

units of surface excess

Answer 2

moln-2

Question 3

changing the surface excess units of molm-2 into amstrong can do what

Answer 3

it can tell us the length of the surfactant molecules

Question 4

mol m-2 to A2 steps

Answer 4

ans x avogadro
gives us molecule m-2

1/ ans = m2 molecule

ans x 10^20 = A per moelcule

aka the distance per molecule aka distance of molecule

Question 5

Se is usually what magnitude

Answer 5

10^-5 // 10^-6

Question 6

surface area is sually what magnitude

Answer 6

50 - 60 A^2

Question 7

when u have a more hydrophobic surfactant what happens

Answer 7

u get more foaming ,, bc less dissolved in the solvent and more will be on the surface

Question 8

what happens when u have a more hydrophilic surfactant

Answer 8

it will dissolve more in the solution so there iwll be no foaming and less adsorption at the surface bc its very oluble in the water.

Question 9

when we think if the bulk what should we think of

Answer 9

micelles

Question 10

gibbs equation

Answer 10

🔺G = 🔺H - T🔺S

Question 11

what is the driving force of micelle formation

Answer 11

find out lols

Question 12

🔺H of micelle formation

Answer 12

very small positive value

bc no bonds are being made /// brokennnn

Question 13

we first think that entropy of aggregation issss and why

Answer 13

we think its negative bc ur going from disordered to more ordered

ur going from 100 free SF to 1 micelle

Question 14

what is acc entropy of micellation !!

Answer 14

negative !!

Question 15

what makes entropy negative in micellation

Answer 15

• translational entropy:
  SF has a hydration shell (water moelcules surrounding the molecule) these interact with it as it moves.

the micelle also has a hydration shell but far less molecules are needed to cover the micelle compared to the individual SF moleules : think surface area wise.
(-) net amount of water.

this means that water is released into the bulk when micelles are formed,, ,increasing the entropy of the bulk!! giving us a negative value

Question 16

apart from translational entropy,, what else contributes to the negative entropy when micelles are formed

Answer 16

u have conformational freedom!!!

the Hc chain has a strongly bound hydration shell that when u aggregate it to form a micelle forms an interior that is just the HC chains,, whihc can move freely as its not surrounded by water!!

when the HC is in water and free i nthe free SF,, it doesnt move much bc its hydrophobic and moving around would increase its interaction with water,, which is unfavourable!!!

so conformational freedom also increases entropy

Question 17

things that make micelle dformation entropically favoured

Answer 17

translational entropy

conformational freedom

Question 18

what do translational entropy and conformational freedom allow

Answer 18

spontaneous micelle formation

bc delta G will be (-)

Question 19

relating 🔺G to CMC,, how many different models are there

Answer 19

2 different models!!