Chapter 18 Free Energy & Thermodynamics Flashcards by Serena Saechia

Define Thermodynamics

Branch of physics concerned with heat and temperature and their relation to energy and work

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Define the 1st Law of Thermodynamics

Conversation of energy; energy can be transformed from one form to another, but can’t be created nor destroyed

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T/F According to the 1st Law of Thermodynamics energy is constant

True

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Define System

The material/process within which we are investigating the energy changes

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Define Surroundings

Anything else that which the system can exchange energy

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What is a good example of System and Surroundings?

Fire and balloon video, the balloon is the system receiving the impact of the fire, the room in which this is taking place is the surrounding, the area that can receive the exchange of energy occurring from the balloon

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Define State Function

Has a value that depends only on the state of the system, not how the system arrived at that state

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Define the 2nd Law of Thermodynamics

States that over time, differences in temperature, pressure and chemical potential tend to disperse in a physical system that is isolated from the outside world

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Define Entropy

A measure of disorder in the system

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The Entropy of the universe is always _____________

Increasing

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In regards to Entropy, energy seems to go from _____________ to ______________

Concentrated; dispersed

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Define Spontaneous

A process that occurs without ongoing input of energy from outside the system (no force, it naturally occurs)

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What are some examples of Spontaneous reactions?

I) Dissolution of NaCl in water

II) Melting of ice above zero degrees celsius

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Define Nonspontaneous

It is the very of Spontaneous reactions, due to the fact that it needs continuous input of energy

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A system going from an ordered state to a disorderly system has entropy that is _________ and is considered a _____________ reaction

Increasing; spontaneous

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What is the equation used for Entropy?

ΔS = S final - S initial

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Spontaneous ΔS…

ΔS > 0 (positive value)

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Nonspontaneous ΔS…

ΔS < 0 (negative value)

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At equilibrium ΔS…

ΔS = 0

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of microstate __________ means _______ disorderly and S __________

Increases; more; increases

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Predict the sign of ΔS for each process below
I) 2KClO3 (s) –> 2KCl (s) + 3O2 (g)
II) N2 (g) + 3H2 (g) –> 2NH3 (g)
III) 2O3 (g) –> 3O2 (g)

I) ΔS is positive b/c gas is generated
II) ΔS is negative b/c gas is reduced
III) ΔS is positive b/c gas is generated

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From solid to liquid to gas, Entropy ΔS __________

Increases

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What is the equation relating Entropy and system exchanging of heat

ΔS = Qrev / T

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What is the process from a Gas to a Liquid phase?

Condensation

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What is the process from a Liquid to a Solid phase?

Freezing

What is the process from a Solid to a Liquid phase?

Melting

What is the process from a Liquid to a Gas phase?

Vaporization

T/F For any spontaneous process, the Entropy of the universe decreases

False; for any spontaneous process, the Entropy of the universe increases (ΔS > 0)

ΔSuniverse = ΔS _______ + ΔS _________

System; surrounding

Exothermic process __________ the Entropy of surroundings

Increases

Endothermic process __________ the Entropy of surroundings

Decreases

Change in Entropy of the surroundings is inversely proportional to what?

To the temperature at which the heat is transferred

What is the equation relating Entropy of surrounding temperature dependence?

ΔS surrounding = -ΔHsystem / T

Higher temperature (T), _______ change in Entropy of surrounding resulting in _______ ΔS surrounding

Less; smaller

Lower temperature (T), _______ change in Entropy of surrounding resulting in _______ ΔS surrounding

More; larger

Define Exothermic Relation to Entropy

Process that emits heat into the surroundings with (-ΔH system)

Exothermic Relation __________ the entropy of the surroundings

Increases

Equation showing Exothermic Relation to Entropy

ΔS = - (-Δ system) / T = +ΔS surrounding

Define Endothermic Relation to Entropy

Process that absorbs heat from the surroundings with (+ ΔH system)

Endothermic Relation __________ the entropy of the surroundings

Decreases

Equation showing Endothermic Relation to Entropy

ΔS = - (+ΔH system) / T = - ΔS surrounding

T/F The magnitude of the change in entropy of surroundings is not directly proportional to the magnitude of systems

False; the magnitude of the change in entropy of surroundings is proportional to the magnitude of systems

Define Gibb's Free Energy (G)

A thermodynamic state function related to Enthalpy (H) and Entropy (S)

T/F Gibb's Free Energy (G) is the minimum amount of work energy that can be released to the surroundings at constant T and P

False; Gibb's Free Energy (G) is the MAXIMUM amount of work energy that can be released to the surroundings at constant T and P

What can Gibb's Free Energy (G) also be known as?

Chemical Potential

What is the equation used for Gibb's Free Energy (G)?

ΔG = ΔHsystem - TΔSsystem

Spontaneous ΔG is...

ΔG < 0

Nonspontaneous ΔG is...

ΔG > 0

ΔG HAS to be __________ to be considered spontaneous

Negative

ΔG ___________ when ΔH __________

Decreases; decreases

ΔG ___________ when T ___________

Decreases; increases

ΔG ___________ when ΔS __________

Decreases; increases

ΔG is proportional to ______________

Negative Delta S universe

To be spontaneous ΔG is _______ and ΔS universe is _______

ΔG < 0; ΔSuniverse > 0

To be nonspontaneous ΔG is ______ and ΔSuniverse is _______

ΔG > 0; ΔSuniverse < 0

If ΔH is negative and ΔS is positive what is the result of ΔG?

ΔG is negative meaning it is spontaneous at all temperatures

If ΔH is positive and ΔS is negative what is the result of ΔG?

ΔG is positive meaning it is nonspontaneous at all temperatures

If ΔH is negative and ΔS is negative what is the result of ΔG?

Since both ΔH and ΔS is negative ΔG's value will be determined by the temperature

When Delta H is negative and Delta S is negative what will Delta G be with regards to temperature?

Negative Delta G (spontaneous) with low temperature | Positive Delta G (nonspontaneous) with high temperature

If ΔH is positive and ΔS is positive what is the result of ΔG?

Since both ΔH and ΔS is positive ΔG's value will be determined by the temperature

When ΔH is positive and ΔS is positive what will ΔG be with regards to temperature?

Negative ΔG (spontaneous) with high temperature | Positive ΔG (nonspontaneous) with low temperature

Define the 3rd Law of Thermodynamics

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

How many ways can you arrange the components in a perfect crystal?

Only one possible way

Define Standard Molar Entropy (S^o)

The entropy of one mole of the substance under standard state at 25 degrees celsius

Entropy __________ when molar mass ___________

Increases; increases

When is the only time you can apply and compare Entropy to molar mass values?

Only apply to elements in the same state (aka same column in the periodic table)

Define Allotropes

Elements that can exist in 2 or more forms

T/F Different arrangements of atoms leads to different standard molar entopies

True

For a given state of matter, Entropy __________ when molecular complexity ___________

Increases; increases

What is the equation used to show Entropy change for chemical reactions?

ΔS^o rxn =Σnp S^o (products) -Σnr S^o (reactants

In the equation ΔS^o rxn =Σnp S^o (products) -Σnr S^o (reactants What does p and r represent?

The stoichiometric coefficients of the products and reactants

Define Standard Change of Free Energy for a Chemical Reaction

The change in free energy between the products and the reactants for a chemical reaction at standard states