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CHEM 14203 > LO 66 - 74 > Flashcards

LO 66 - 74 Flashcards

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1
Q

What is nature’s heat tax?

A

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

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2
Q

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

A

spontaneous

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3
Q

Are nonspontaneous processes impossible?

A

No

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4
Q

Can a nonspontaneous process become spontaneous?

A

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

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5
Q

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

A

Intermediate states, speed
Initial and final states, spontaneity

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6
Q

Are all spontaneous processes fast?

A

No, spontaneous only indicates direction and extent not rate

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7
Q

__________ is the spreading out of energy.

A

entropy (S)

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8
Q

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

A

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

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9
Q

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

A

macrostate
microstate

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10
Q

Increased entropy of a state means ________ dispersal of energy

A

greater

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11
Q

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

A

the entropy of the universe MUST increase

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12
Q

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

A

increases the entropy

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13
Q

Rank the states of matter from lowest to highest entropy

A

solid < liquid < gas

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14
Q

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

A

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

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15
Q

What are the units of entropy?

A

Joules/Kelvin

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16
Q

Equation to determine the change in ΔS universe

A

ΔS universe = ΔS system + ΔS surroundings

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17
Q

Exothermic processes (-ΔH) ________ ΔS surroundings

A

increase

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18
Q

Endothermic processes (+ΔH) ___________ ΔS surroundings

A

decrease

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19
Q

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

A

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

20
Q

What is the formula for ΔS surroundings?

A

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

21
Q

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

A

exothermic
negative
positive

22
Q

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

A

endothermic
positive
negative

23
Q

ΔS° system = . . .

A

∑S° products - ∑S° reactants

24
Q

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

A

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

25
Q

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

A

Gibbs free energy
ΔG = ΔH - TΔS

26
Q

How is ΔG related to the enthalpy of the universe?

A

ΔG = -T · ΔS universe

27
Q

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

A

spontaneous

28
Q

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

A

nonspontaneous

29
Q

The MORE negative ΔG, the more ___________ a process

A

spontaneous

30
Q

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

A

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

31
Q

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

A

Standard ΔS° rxn

32
Q

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

A

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

33
Q

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

A

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

34
Q

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

A

one mol

35
Q

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

A

greater
only for compounds all in the same state

36
Q

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

A

less

37
Q

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

A

increasing

38
Q

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

A

increase

39
Q

ΔG° rxn = _______________________

A

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

40
Q

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

A

multiplied by the same factor

41
Q

If a chemical equation is reverse, ΔGrxn . . .

A

changes signs

42
Q

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

A

sum

43
Q

When ΔG°rxn is positive it represents the _____________________________________

A

minimum amount of energy required for the reaction to occur

44
Q

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

A

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

45
Q

ΔG° rxn = __________ given the equilibrium constant K

A

-R · T · ln(K)

46
Q

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

A

negative
positive
reverse

47
Q

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

A

positive
negative
forward

CHEM 14203 (18 decks)

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