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physical - yr2, s1 > 4d > Flashcards

4d Flashcards

1
Q

what is entropy a function of

A

entropy is a function of state

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2
Q

Sa and Sb relate to what

A

they relate to different states

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3
Q

when Sa and Sb are plotted on a graph,, what are the axis

A

u have volume on the Y
and temperature on the X

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4
Q

what does Sb - Sa equal

A

difference in entropy

dS = dQ/T

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5
Q

is dQ and sQ state functions

A

nopeee

to think of Q.

u need to do dS = dQ/T

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6
Q

how to make heat a state functio, q or Q

A

we add temperature to the mix!!

so dS = dQ / T

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7
Q

what does dQ/T equal if the process is reversible

A

if dQ/T is reversible it will equal 0.

aka it makes a complete circle and the reaction starts and ends at the same point.

so tbh we dont rlly know if the reation occured or not.

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8
Q

what will dQ/T equal if the process is irreversible

A

if its irreversible dQ/T will be smaller than 0.

we would be able to see that the reaction took place bc it doesnt start and end at the same time

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9
Q

dQ/T (aka change in entropy) when the process is reversible =

A

0

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10
Q

dQ/T is the process is irreversible

A

< 0

smaller than 0.

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11
Q

for a system in an environment: entropy change of the system will be

A

smaller or equal to 0

aka dQ/T < 0 or equal to

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12
Q

for a system in an environment: entropy change of theenvironment will be

A

> 0

equal to 0 or positive.

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13
Q

in areversible reaction.. what is hard to clock

A

its hard to clock if the reaction actually took place.

bc dS aka dQ/T is equal to 0.

so if change is 0,, how do we know if anything actually happened.

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14
Q

in an irreversible system,, what is dS and what is dQ/T

A

dS is 0. meaning it starts and ends at the same entropy level.

dQ/T < 0 : this is change in heat exchange: which can tell us if a process has occured bc it doesnt start and end at 0.

dQ/T < 0

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15
Q

in an irreversible reaction,, dS = 0,, so we cant tell if a reaction takes place,, but what can we use to tell if it takes place and what equation is it

A

dS = 0

but yk what doesnt equal to 0.

dQ/T aka heat exchange does not equal to 0.

dQ/T < 0 !!!!

so we can use it to see if smt has acc happened.

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16
Q

e is used for what

A

to tell us were talking about the environment

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17
Q

what does i tell us about

A

tells us were talking about the internal

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18
Q

diS corresonds to the irreversible part which equals to

A

not zeroooooo

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19
Q

dis stands for what

A

internal entropy change

which doesnt equal to 0

and is the irreversible part

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20
Q

dS = what in terms of i and e

A

dS = diS + deS = 0

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21
Q

e =

A

exchange of matter and energy

entropy difference of the system

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22
Q

i =

A

entropy change related to irreversible processes within the system

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23
Q

diS goes from being smaller than what,,, to being bigger than what when introducing an irreversible process

A

diS goes from being smaller than 0

to being larger than 0

when introducing an irreversible system

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24
Q

what isnt exchanged in a closed system

A

no matter exchange.

deS = dQ/T

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25
Q

id diS is smaller than 0 ,, what must deS be

A

deS must be bigger than 0.

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26
Q

so if dS is equal to 0,, and diS is smaller than 0,, what must deS be

A

deS must be bigger than 0.

e for enormous,, aka larger than 0.

diS = incey wincey = small so smaller than 0.

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27
Q

diS is smaller or larger than 0

A

diS is smaller than 0

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28
Q

deS is smaller or larger than 0

A

deS is larger than 0

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29
Q

deS anddiS must do what to eachother

A

they should cancel eachother out

bc dS needs to be 0.

30
Q

okay so in an irreverisble read=ction,, normall dS is equal to what

A

normal dS needs to be < dQ/T

31
Q

but in an irreversible reaction §dS = what

A

§dS = 0

32
Q

reversible reactionnnn:
dS =
§dS =

A

dS = dQ/T

§dS = §dQ/T = 0

33
Q

in an irreverible reaction
dS =
§dS = 0
§dQ/T =

A

dS < dQ/T

§dS = 0

§dQ/T < 0

34
Q

so if §deS = §dQ/T < 0 what does this mean

A
  • for a system to return to its initial state

the entropy generated by irreversible processes within the system

heat must be exchanged to the exterior, increasing the entropy of the exterior

35
Q

every process in nature does what

A

every process in nature increases entropy

36
Q

what cool thing does entropy let us do

A

it lets us distinguish the past from the future

it can thereore help us predict the direction in which a system will evolve. direction of the process // reaction

so even if the reaction is reverisble,, it leaves a trace on the env,, so we can see the direction and acc realise if a reaction has occured or not.

37
Q

what reaction is the cool one that tells us that entropy change can tell us if a reversible reaction has occured.

A

§deS = §dQ/T = < 0

38
Q

1st law is what,, and what is the equation

A

1st law is conservation of energy

dU (closed system) = dQ + dw

39
Q

if dS of a closed system is 0,, what does this mean

A

it means that the reaction is reverisble.

40
Q

dS = whatttttt

A

dQ/T

41
Q

dU in terms of temp, entropy and work

A

dU = TdS + dW

42
Q

dU in terms of T , S , p and v

A

dU = TdS - pdV

43
Q

what is entropy + can we use it to predict the direction of a reaction

A

every process increases entropy// so there must be something favourable about it

measure of disorder.

and lowkey everything loves disorder soooo

44
Q

what did boltzman do

A

boltzman associated entropy with disorder + probability

entropy,, disorder,, probability.

45
Q

S aka entropy is proportionate to whattt

A

ln( W)
which is the number of microstates

based on observation so no need for the super hardcore science stuff.

46
Q

S in terms of boltzman

A

S = kB x ln(W)

entropy = boltzman constant x ln( W )

W being the number of microstates.

47
Q

what remains constant in an adiabatic process

A

temperature remains the same in an adiabatic process!!

it means temp constant

48
Q

when were thinking of S = KB x ln(w) what should we always think offff

A

think of a box with a barrier,, in the middle

with amount of dots in each side of the box on opp sides of the barrier!!!!!!!

49
Q

in the boltzman box,, S = kb x ln(w)

what does N mean

A

N is the number of particles of gas on each side of the box,, on each side of the barrier.

50
Q

N1 + N2. = what

A

N

aka N 1 = number of gas particles on one side of the boltzman box

N2 = number of particles on the other side of the boltzman box

51
Q

the barrier in the boltzman box is

A

its permeable so an equilibrium can be met bc particles can move to opp sides of the box.

52
Q

what do we need to try and max out

A

we want to max out S of the boltzman entropy thing

so we want to max out W. the number of microstates.

so we need to balance the number of particles on each side of the box!!!

53
Q

what is W

A

( N1 + N2) ! // N1! N2!

so kinda like reduced mass but u add the ! to it.

54
Q

a symmetric distribution of particles in the boltzman distribution is what

A

its wantedddd

bc it maxes out W

which maxes out S.

which is what we want

bc W = (N1 + N2)! // N1! N2!

55
Q

microstates with a larger W are what

A

theyre more probable

56
Q

if the distribution is asymmetrical,, W is reduced which means what else is redued

A

it means that the equilibrium state is also reduced.

57
Q

the boltzman box this only occurs in what type of reaction

A

a irreversible entropy increase

it doesnt work in a reversible reaction bc if u want to max out W and there fore the equilibrium state and S.

once youve finally got a symmetric distribution,, why would u want to reverse that and get an asymmetric distributio again?/

58
Q

the distribution that corresponds to the equilibrium is what one

A

the one that maxes out W and therefore S.

aka the one with the most symmetric distribution.

bc S = Kb x ln(w)

59
Q

what leaves a trace on the environment in a reversible reaction

A

entropyyyyyy. the past and present thing we were one about to see if a reaction acc took place.

60
Q

what can we use S to do

A

S can be used to predict the direction of a reaction.

61
Q

if we have a box,, lhs and rha = what

A

lhs = T1

rhs = T2

T1 would be larger than T2,, meaning there is heat flux from T1 to T2 aka from the lhs to the rhs.

making dQ positive ,, making diS > 0 .

62
Q

diS thereofre isss

A

-dQ/T1 + dQ/T2

= ( - 1/T1 + 1/T2) dQ

63
Q

so diS / dT =

A

(-1/T1 + 1/T2) dQ/dT

meaning S depends on diff in temp!!!!

chnage in S /T

64
Q

when heat flux occurs,, heat is moved from high temp to low temp,, soon the equilibrium will be established and the temp change will be 0 ,, when this occurs what happens

A

the rate of S will vanish and we reach the minimum equilibrium state.

65
Q

plot of rate of exchange : diS/dT ,, with T1-T2 on the axis.
> 0

at equilibrium the rate function will be

A

at the minnnnn

aka when T1 is hotter than T2 meaning their difference is (+) and thereofore above 0.

rate of exchange is at its min.

smiley face smile

66
Q

graph when S is plotted against (T1 - T2)

A

maxxxxxx

hill shape!!!

67
Q

when the temp difference is largeu gettt

A

maxxx

68
Q

when temp diff is small u get

A

minnnnn

69
Q

rate =

entropy =

A

= min

= max

70
Q

the thing that maximises the states corresponds to theee

A

equilibrium

71
Q

non eq to equilibrium

how does W and S work

A

W ne < W
S ne < Se

so we want equilibrium!!!!

physical - yr2, s1 (23 decks)

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