Chapter 3 SYDNEY

Question 1

A spontaneous change occurs
___________ continuous input of
energy into the system from
outside

Answer 1

without

Question 2

A nonspontaneous process
requires_________ input of
energy

Answer 2

constant

Question 3

Spontaneous in one direction
means ____________ in
opposite direction

Answer 3

non-spontaneous

Question 4

_______________ processes involve ordered motion becoming
random and localized energy becoming dispersed

Answer 4

Spontaneous (Non-spontaneous processes involve the reverse)

Question 5

Thus, dispersal of matter and energy tends to be
______________ while the concentration of matter
and energy tends to be non-spontaneous

Answer 5

spontaneous

Question 6

Second Law of Thermodynamics

Answer 6

Heat does not flow spontaneously
from a cool body to a hotter body

Question 7

The Second Law can be expressed in terms of a new state function, _____________

Answer 7

entropy

Question 8

The entropy of an isolated system __________ in the course of a spontaneous change: ΔStot > 0

Answer 8

increases

Question 9

Thermodynamically irreversible changes always have ______________

Answer 9

ΔStot > 0

Question 10

define entropy in thermodynamics
according to the what equation?

Answer 10

𝑑𝑆 = 𝑑𝑞𝑟𝑒𝑣/T & ∆𝑆 = ׬𝑖
𝑓 𝑑𝑞𝑟𝑒𝑣/T

Question 11

In some processes, ΔSsys is negative (energy or matter is getting concentrated, not dispersing) but can still be spontaneous if _______________

Answer 11

spontaneously if ΔSsur is sufficiently positive that ΔStot > 0

Question 12

What are some examples of spontaneous processes where ΔSsys is positive?

Answer 12

Gas expanding
– Water evaporating

Question 13

What are some examples of spontaneous processes where ΔSsys is negative?

Answer 13

-Water condensing on a cold glass
– Water freezing from a liquid to a solid in the freeze

Question 14

So, 𝑑𝑞𝑟𝑒𝑣/𝑇 is essentially the _______________ value for the change in entropy for a process; it could be more

Answer 14

minimum

Question 15

units of entropy are
what?

Answer 15

J/K

Question 16

Entropy is an ____________ property, so amount of entropy depends on system size

Answer 16

extensive

Question 17

What is the equation used for entropy and the surrounding?

Answer 17

∆𝑆𝑠𝑢𝑟 = 𝑞𝑠𝑢𝑟/ T sur

Question 18

we generally assume that the
surroundings are held at a __________ temperature and either constant volume or constant pressure

Answer 18

constant

Question 19

what is ∆𝑆𝑠𝑢𝑟 for an adiabatic
process?

Answer 19

∆𝑆𝑠𝑢𝑟 = 0

Question 20

In statistical mechanics, entropy is defined via the Boltzmann equation as what?

Answer 20

𝑆 = 𝑘 ln 𝒲 & 𝑆 = 𝑘 ln Ω (where 𝒲 or Ω represent the number of microstates possessed by a state with a given internal energy. k is
the Boltzmann constant: k = 1.380649×10−23 J⋅K−)

Question 21

microstate

Answer 21

snapshot of a state at the molecular level

Question 22

A microstate is described by the individual positions and ________________ of every atom

Answer 22

velocities

Question 23

There are generally huge numbers of ____________ microstates – microstates with the same values of the macroscopic variables P, V, T, and n

Answer 23

equivalent

Question 24

Less constrained systems (like gases) have ________ equivalent microstates

Answer 24

more

Question 25

More constrained systems (like solids) have _______ equivalent microstates

Answer 25

fewer

Question 26

An analogy to states and microstates using _______

Answer 26

dice (The state is the sum of the values on the dice
– The microstate is the specific set of values rolled)

Question 27

The Carnot Cycle involves ______ steps and is an idealized representation of an engine that produces work from heat

Answer 27

4

Question 28

To calculate the entropy change associated with a given process (expansion, phase transition,
heating, etc.), find a _________ path between initial and final state.

Answer 28

reversible

Question 29

Equation for Isothermal expansion of an ideal gas (of the system)

Answer 29

∆𝑆 = 𝑛𝑅 ln 𝑉𝑓/Vi (If process is reversible, ∆𝑆𝑠𝑦𝑠= −∆𝑆𝑠𝑢𝑟
– In that case, ∆𝑆𝑡𝑜𝑡= ∆𝑆𝑠𝑦𝑠 + ∆𝑆𝑠𝑢𝑟=0)

(However, if expansion is against a fixed pressure,
∆𝑆𝑡𝑜𝑡≠ 0
– Specifically, if it is free expansion (against a vacuum),
∆𝑆𝑠𝑢𝑟= 0, so ∆𝑆𝑡𝑜𝑡 = 𝑛𝑅 ln 𝑉)

Question 30

In physical chemistry, a change in physical state (solid→liquid; liquid→gas) is usually called a
________________

Answer 30

phase transition

Question 31

To analyze a phase transition, we limit ourselves to consider the process at the normal _________________

Answer 31

transition temperature, Ttr (At this temperature, the 2 phases are in equilibrium
– Thus, the process is reversible in either direction)

Question 32

If 𝑞 = ∆𝑡𝑟𝑠𝐻 is the heat involved in the phase transition, we can easily find ΔS with what equation?

Answer 32

∆𝑡𝑟𝑠𝑆 = ∆𝑡𝑟𝑠𝐻/ Ttrs

Question 33

However, in exothermic processes, because ∆𝑡𝑟𝑠𝑆 <0, ∆𝑆𝑠𝑢𝑟 must be ____________

Answer 33

positive

Question 34

For endothermic processes, heat is entering the system, so _______

Answer 34

∆𝑡𝑟𝑠𝑆 > 0

Question 35

Heat leaving the surroundings means ____________

Answer 35

∆𝑆𝑠𝑢𝑟< 0

Question 36

If both system and surroundings are at Ttrs, they
are in equilibrium and ∆𝑆𝑠𝑢𝑟= _______

Answer 36

-∆𝑡𝑟𝑠𝑆

Question 37

Nernst Heat Theorem

Answer 37

The entropy change accompanying any physical or chemical transformation approaches zero as
the temperature approaches 0: ΔS→0 as T→0 provided all the substances involved are perfectly
ordered

Question 38

Third law of entropy

Answer 38

The entropy of all perfect crystalline substances is zero at T=0 K

Question 39

The entropy of a pure substance in its standard state is called its __________ “Third-Law” entropy
or just its standard entropy

Answer 39

standard

Question 40

Generally, reactions that result in a net increase in gas will have ___________ ∆𝑟𝑆𝑜, while reactions that result in a net decrease in gas will have negative ∆𝑟𝑆𝑜

Answer 40

positive

Question 41

With ___________ equation, we now have expressions for conditions for spontaneous processes that only
include properties of the system

Answer 41

Helmholtz

Question 42

The change in Helmholtz energy is equal to the ___________ work that can accompany a process at
constant temperature

Answer 42

maximum

Question 43

If a reaction has ΔG < 0, it is ____________

Answer 43

spontaneous

Question 44

If a reaction has ΔG > 0, the __________ reaction is spontaneous

Answer 44

reverse

Question 45

A system at equilibrium has ΔG = ?

Answer 45

Zero