2nd law of Thermodynamics and entropy Flashcards

1
Q

2nd law of Thermodynamics

A

in isolated system, entropy can only increase

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2
Q

change of entropy

A

proportional to heat transferred from system to surroundings

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3
Q

change of entropy equation

A

DS>= Dq/T

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4
Q

Dq

A

change of heat (s)

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5
Q

T

A

temperature

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6
Q

change in entropy at equilibrium

A

DS=Dq/T

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7
Q

entropy equation depends inversely on temp

A

-DS=Dq/T

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8
Q

equation of entropy change of surroundings

A

DS(surr) = Dq(surr)/T

or -DS=DH(surr)/T (DH=Dq at constant pressure)

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9
Q

changes in exothermic reaction

A

entropy of system decreases

entropy of surroundings increases as energy is transferred out

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10
Q

changes in endothermic reaction

A

entropy of system increases

entropy of surroundings decreases as energy if transferred in

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11
Q

how to make a spontaneous reaction

A

total of entropy of system + surrounding must be >0

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12
Q

equation for a spontaneous reaction

A

DS(total) = DS(system) + DS(surr) >0

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13
Q

why does water freeze at -10 and not 10 degrees celsius

A

finding DS(surr) for each
temperature used in kelvin
DS(system) is -22Jk-1mol-1
find DS(total) and find which reaction occurs

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14
Q

Gibbs free Energy (DG)

A

energy from reaction that is available to generate work

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15
Q

equation for DG

A

DG = DH - TDS

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16
Q

quantities of systems

A

macrostate and microstate

17
Q

macrostate system

A

temperature, pressure, volume

AKA collection of microstate

18
Q

microstate system

A

kinetic energy, force, velocity

19
Q

macrostate at equilibrium

A

does not change over time

microstates can be specified at anytime

20
Q

entropy in the concept of system

A

(S) no. microstates of system

21
Q

nr of microstates at given total energy

A

W(E)

22
Q

W entropy

A

omega

23
Q

Boltzmann contrast

A

Kb = 1.38064852*10 to power -23 m2kgS-2k-1

24
Q

entropy equation

A

S = Kb*In(W)

25
Q

consequences of increasing no. particles(N)

A

using binomial distribution

26
Q

equation of particles binomial distribution - P(N,NL)

A

N!/ (N-NL)!NL! *1/2N

27
Q

nature of equilibrium width in graph

A

width of distribution =total no. macrostates

gets narrower with around 1/sq root(N)

28
Q

increase in size of system

A

better defined equilibrium value

29
Q

example of 2 boxes and 4 particles on one side and when open how many will go to the other side
(labelling)

A

system - 2 boxes
macrostate - NL no.particles on left
microstate - W(4,NL) particular configuration of 4 particles in system

30
Q

example of 2 boxes and 4 particles on one side and when open how many will go to the other side (method)

A
  • no. particles in NL (0,1,2,3,4)
  • W(4,NL) - binomial distribution
  • divide W(4,NL) by W(total)
31
Q

example of 2 boxes and 4 particles on one side and when open how many will go to the other side (total)

A

total microstate 16 - W(total)

able to be plotted on a graph( bar chart)