Chapter 19: Thermochemistry

Question 1

second law of thermodynamics:

Answer 1

the pervasive tendency for energy to spread out or dissipate when not prevented from doing so

Question 2

the second law determines…

Answer 2

spontaneous direction of all processes

Question 3

spontaneous process occurs..

Answer 3

without outside intervention

Question 4

what is the spontaneity of a reaction?

Answer 4

the direction in which, and the extent to which, a chemical reaction proceeds

Question 5

a rxn may be thermodynamically spontaneous but kinetically BLANK at a give temp

Answer 5

slow

Question 6

what effect does a catalyst have on a chemical rxn

Answer 6

the rate of a spontaneous process can be increased by a catalyst, but a nonspontaneous process can’t be made spontaneous by te use of a catalyst

Question 7

thermodynamics deals with the relative chemical potentials of the BLANK and BLANK

Answer 7

reactants and products

Question 8

how can a nonspontaneous process be made spontaneous?

Answer 8

by coupling the nonspontaneous rxn to another process that is spontaneous or by supplying energy from an external source

Question 9

most spontaneous processes are what kind of rxns

Answer 9

exothermic

Question 10

what type of process do you have when a highly ordered arrangement goes to a disorderly arrangement

Answer 10

spontaneous

Question 11

entropy:

Answer 11

quantity related to disorder or randomness at the molecular level

Question 12

sign for entropy

Answer 12

S

Question 13

what are the units of entropy

Answer 13

J/K

Question 14

if conditions P,V, and T remain constant, the energy of the system..

Answer 14

also remains constant

Question 15

microstate:

Answer 15

exact internal energy distribution among the particles at any one instant

Question 16

microstate in simpler terms:

Answer 16

snapshot of the system at a given instant in time

Question 17

macrostate:

Answer 17

composed of several microstates, each with a different number of molecules and/or different arrangement of molecules

Question 18

greater entropy says what about arrangment?

Answer 18

greater entropy means more energetically equivalent ways to arrange the components of a system

Question 19

if state A is highly dispersed and state B is highly concentrated, which has the higher entropy?

Answer 19

state A

Question 20

processes that decrease the entropy of the university occur spontaneously or nonspontaneously

Answer 20

nonspontaneously

Question 21

entropy is what kind of function?

Answer 21

state function

Question 22

formula for change in entropy:

Answer 22

change in S = Sfinal - Sinitial

Question 23

chemical system proceeds in a direction that BLANK the entropy of the universe

Answer 23

increases

Question 24

A gas has more BLANK than a solid

Answer 24

microstates

Question 25

a change in state is accompanied by an exchange of

Answer 25

heat between the system and surroundings

Question 26

equation for change in entropy at constant temperature

Answer 26

change in S = (qreverse)/T

Question 27

All reversible processes are in a constant…

Answer 27

state of equilibrium

Question 28

formula for entropy of universe:

Answer 28

change S universe = (change in S system) + (change S surroundings)

Question 29

an exothermic process BLANK entropy of surroundings

Answer 29

increases

Question 30

an endothermic process BLANK entropy of surroundings

Answer 30

decreases

Question 31

The greater the temperature, the smaller the BLANK in entropy for a given amount of energy dispersed into the surroundings

Answer 31

increase

Question 32

the higher the temperature the BLANK the impact

Answer 32

smaller

Question 33

at low temperatures, the decrease in entropy of the system is BLANK by the large increase in the entropy of the surroundings

Answer 33

overcome

Question 34

the change in entropy of the surroundings depends on what two things?

Answer 34

(a) the amount of heat transferred into or out of the surroundings
(b) the temperature of the surroundings

Question 35

first law of thermodynamics:

Answer 35

any heat leaving the system must go into the surroundings and vice versa

Question 36

A process that emits heat into the surroundings does what to the surroundings?

Answer 36

increases the entropy of the surroundings

Question 37

A process that absorbs heat from the surroundings does what to the surroundings?

Answer 37

decreases the entropy of the surroundings

Question 38

exothermic processes have a tendency to be spontaneous at what temperatures

Answer 38

low temperatures

Question 39

formula for free energy:

Answer 39

change in G = enthalphy - T*entropy

Question 40

a negative value of G corresponds to :

Answer 40

spontaneous process

Question 41

what values of for enthalpy and entropy produce a process that is spontaneous at all temperatures?

Answer 41

negative H, positive S… because entropy of both system and surroundings increases

Question 42

what values of for enthalpy and entropy produce a process that is not spontaneous at all temperatures?

Answer 42

postive H, negative S

Question 43

negative H and negative S yields a spontaneous process at what temperatures

Answer 43

low temperatures

Question 44

formula for standard entropy of rxn

Answer 44

Srxn = Sproducts - S reactants

Question 45

third law of thermodynamics:

Answer 45

the entropy of a perfect crystal at absolute zero (0K) is zero

Question 46

allotropes

Answer 46

elements that exist in two or more forms within the same state

Question 47

as molar mass increases, what happens to standard entropies?

Answer 47

increase

Question 48

allotropes that allow for more freedom of molecules have what kind of standard entropies?

Answer 48

greater entropies

Question 49

how does increasing molecular complexity affect entropy

Answer 49

entropy increases

Question 50

The dissolution of a crystalline solid into solution usually results in an BLANK in entropy

Answer 50

increase