LO 66 - 74

Question 1

What is nature’s heat tax?

Answer 1

on every energy transaction, some energy is lost/dissipated as heat to the surroundings

Question 2

______ processes occur without outside intervention such as work by an external force

Answer 2

spontaneous

Question 3

Are nonspontaneous processes impossible?

Answer 3

No

Question 4

Can a nonspontaneous process become spontaneous?

Answer 4

Yes, under a change in surrounding conditions OR if paired with another spontaneous process

Question 5

Kinetics have to do with the ____________ and _______ of a reaction while thermodynamics have to do with the __________ and ___________ of a reaction

Answer 5

Intermediate states, speed
Initial and final states, spontaneity

Question 6

Are all spontaneous processes fast?

Answer 6

No, spontaneous only indicates direction and extent not rate

Question 7

__________ is the spreading out of energy.

Answer 7

entropy (S)

Question 8

In the equation S = K · ln(W) what is W?

Answer 8

The number of energetically equivalent ways to arrange components in a system / microstates within a macrostate

Question 9

A given set of conditions (P,V,T) describes a system’s __________ and remains constant as long as conditions are constant. The __________ describes the exact internal energy distribution of a system

Answer 9

macrostate
microstate

Question 10

Increased entropy of a state means ________ dispersal of energy

Answer 10

greater

Question 11

For any spontaneous process, how must the S of the universe be affected?

Answer 11

the entropy of the universe MUST increase

Question 12

A chemical reaction will proceed in the direction that ____________ of the universe

Answer 12

increases the entropy

Question 13

Rank the states of matter from lowest to highest entropy

Answer 13

solid < liquid < gas

Question 14

When determining the change in entropy of a gaseous reaction . . .

Answer 14

final gaseous mols - initial gaseous mols UNLESS you are working with a phase change of a single compound

Question 15

What are the units of entropy?

Answer 15

Joules/Kelvin

Question 16

Equation to determine the change in ΔS universe

Answer 16

ΔS universe = ΔS system + ΔS surroundings

Question 17

Exothermic processes (-ΔH) ________ ΔS surroundings

Answer 17

increase

Question 18

Endothermic processes (+ΔH) ___________ ΔS surroundings

Answer 18

decrease

Question 19

The greater the temperature of the surroundings, the ________ the increase in entropy because . . .

Answer 19

smaller
entropy represents the energy dispersed in a sample of matter PER unit temp.

Question 20

What is the formula for ΔS surroundings?

Answer 20

ΔS surr. = (-ΔH system)/T
In kelvin at constant pressure and temp.

Question 21

a process the emits heat is ____________ with a _______ ΔH system but _________ ΔH surroundings

Answer 21

exothermic
negative
positive

Question 22

a process the absorbs heat is ____________ with a _______ ΔH system but _________ ΔH surroundings

Answer 22

endothermic
positive
negative

Question 23

ΔS° system = . . .

Answer 23

∑S° products - ∑S° reactants

Question 24

Given only the change in system energy, how would you calculate ΔS universe?

Answer 24

ΔS universe = ΔS system - (ΔH system/T)

Question 25

_______ can be used to relate entropy to enthalpy of a system using the equation . . . (hint: GHAST)

Answer 25

Gibbs free energy ΔG = ΔH - TΔS

Question 26

How is ΔG related to the enthalpy of the universe?

Answer 26

ΔG = -T · ΔS universe

Question 27

A decrease in Gibbs (ΔG < 0) corresponds to a _______ process

Answer 27

spontaneous

Question 28

An increase in Gibbs (ΔG > 0) corresponds to a __________ process

Answer 28

nonspontaneous

Question 29

The MORE negative ΔG, the more ___________ a process

Answer 29

spontaneous

Question 30

The temperature at which ΔG changes sign indicates . . . can be determined by setting ΔG = 0 in the equation . . .

Answer 30

Where a reaction goes from spontaneous to nonspontaneous and vise verse. ΔG = 0 = ΔH - TΔS

Question 31

The _________ is the change in entropy for a process in which reactants and products are in the standard states

Answer 31

Standard ΔS° rxn

Question 32

ΔS° rxn = _______________________ with standard molar entropy values (S°) typically given by table

Answer 32

∑np S° products - ∑nr S° reactants where np and nr represent the stoichiometric coefficients for each product reactant

Question 33

The entropy of a perfect crystal at 0° K is equal to _________ because . . .

Answer 33

0 it is the only possible way to arrange components, and too cold for vibrations

Question 34

At 25°C, the standard entropy of any substance is the energy dispersed into __________ of the substance at that temp.

Answer 34

one mol

Question 35

The greater the molar mass of a compound, the _________ the entropy BUT under what condition?

Answer 35

greater only for compounds all in the same state

Question 36

Allotropes with more ridged structures such as diamond have ________ entropy and those that are more amorphous

Answer 36

less

Question 37

Entropy increases with _________ molecular complexity, i.e. more atoms, bonds, lone pairs

Answer 37

increasing

Question 38

The dissolution of a crystalline solid results in an _________ in entropy

Answer 38

increase

Question 39

ΔG° rxn = _______________________

Answer 39

= ΔH°rxn - TΔS°rxn = ∑np G° products - ∑nr G° reactants

Question 40

If a chemical equation is multiplied by some factor, ΔGrxn is . . .

Answer 40

multiplied by the same factor

Question 41

If a chemical equation is reverse, ΔGrxn . . .

Answer 41

changes signs

Question 42

If a chemical equation is represented as its elementary steps, ΔGrxn overall is the ____________ of each steps' ΔG

Answer 42

sum

Question 43

When ΔG°rxn is positive it represents the _____________________________________

Answer 43

minimum amount of energy required for the reaction to occur

Question 44

How do you relate standard state ΔG°rxn to nonstandard state?

Answer 44

ΔGrxn = ΔG°rxn + RT · ln(Q) - Q reaction quotient - T in kelvin - R = 8.314 J/mol K

Question 45

ΔG° rxn = __________ given the equilibrium constant K

Answer 45

-R · T · ln(K)

Question 46

When K < 1, ln(K) is ________ and ΔG° rxn is __________. Under standard conditions (when Q=1), the reaction is spontaneous in the _________ direction

Answer 46

negative positive reverse

Question 47

When K > 1, ln(K) is ________ and ΔG° rxn is __________. Under standard conditions (when Q=1), the reaction is spontaneous in the _________ direction

Answer 47

positive negative forward