Gibb’s Energy & Thermodynamics Flashcards

1
Q

What does entropy describe?

A

the dispersion of energy

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2
Q

What is a spontaneous process?

A

occurs without ongoing external intervention

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3
Q

Can spontaneous reactions be slow?

A

yes

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4
Q

What is entropy? (definition)

A

a thermodynamic function that increases with the number of equivalent ways to arrange the energy among components of the system to acheive a particular overall state

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5
Q

How is entropy mathematically described? What are the variables?

A

S=klnW

S is entropy, k is a constant (1.38x10^-23 JK^-1), W is the # of equivalent energy arrangments in the system (microstates)

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6
Q

Explain why water has greater entropy than ice using microstates?

A

more ways to distribute the energy in water than ice because they can more more, therefore more microstates

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7
Q

What is the second law of thermodynamics?

A

for any spontaneous process the entropy of the universe increases

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8
Q

How do non-spontaneous reactions effect the entropy of the universe?

A

do not increase or decrease it

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9
Q

What is the formula for the change in entropy?

A

deltaS=Sfinal-Sinitial

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10
Q

If entropy increases how does temperature change?

A

increases

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11
Q

What increases entropy?

A

adding more particles, melting, sublimation, evaporation

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12
Q

What is the formula for the entropy of the universe?

A

Suniverse=Ssys + Ssurr

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13
Q

How does the entropy of the surroundings change for exo/endothermic reactions?

A

exothermic increases the entropy of surroundings

endothermic decreases the entropy of surroundings

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14
Q

At a constant temperature and pressure how can you find the entropy of the surroundings?

A

deltaSsurr=-deltaHsys/T (kelvin)

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15
Q

How can you find the change in entropy of the universe?

A

deltaSuni=deltaSsys - deltaH/T

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16
Q

How is Gibb’s free energy related to entropy?

A

deltarG=deltarH - TdeltarS

17
Q

If enthalpy is exothermic and the entropy increases what is the sign for gibb’s free energy?

A

always negative no matter the temperature

18
Q

If enthalpy is endothermic and the entropy decreases what is the sign for gibb’s free energy?

A

always positive, no matter the temperature

19
Q

If enthalpy is exothermic and the entropy decreases what is the sign for gibb’s free energy?

A

negative at a low temperature and posititve at a high temperatureq

20
Q

If enthalpy is endothermic and the entropy increases what is the sign for gibb’s free energy?

A

posititve at a low temperautre and negative at a high temperautre

21
Q

How can you calculate deltarS0?

A

the sum of coefficients multiplied by standard molar entropies of the products minus the sum of coefficients multiplied by standard molar entropies of the reactants

like standard enthalpy

22
Q

What is the enropy of a pure crystal at 0K?

A

0

23
Q

How does molar mass contribute to entropy?

A

heavier atoms have a higher entropy, larger noble gases have a higher entropy

24
Q

How does molecule complexity relate to entropy?

A

more complex molecules have a higher entropy

25
Q

What are the methods to calculate deltarG0?

A

using standard Gibb’s energy of formation, table is only valid for 298K, calulate standard enthalpy and standard entropy and have T, similar to hess law

26
Q

At standard state conditions what is Q?

A

1

27
Q

If deltarG0 is greater than 0, what is the relationship between Q and K?

A

Q is greater than K

28
Q

If deltarG0 is less than 0, what is the relationship between Q and K?

A

Q is less than K

29
Q

If deltarG0 is equal to 0, what is the relationship between Q and K?

A

Q is equal to K

30
Q

How can you calculate deltarG under non standard conditions?

A

deltarG=deltarG0 + RTlnQ

31
Q

How can you find deltarG0 if you know K?

A

deltarG0=-RTlnK

32
Q

If you have two K’s and two temperautre what formula can you use?

A

ln(K2/K1)=-deltarH0/R(1/T2-1/T1)