Chapter 18 Free Energy & Thermodynamics Flashcards
Define Thermodynamics
Branch of physics concerned with heat and temperature and their relation to energy and work
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
T/F According to the 1st Law of Thermodynamics energy is constant
True
Define System
The material/process within which we are investigating the energy changes
Define Surroundings
Anything else that which the system can exchange energy
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
Define State Function
Has a value that depends only on the state of the system, not how the system arrived at that state
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
Define Entropy
A measure of disorder in the system
The Entropy of the universe is always _____________
Increasing
In regards to Entropy, energy seems to go from _____________ to ______________
Concentrated; dispersed
Define Spontaneous
A process that occurs without ongoing input of energy from outside the system (no force, it naturally occurs)
What are some examples of Spontaneous reactions?
I) Dissolution of NaCl in water
II) Melting of ice above zero degrees celsius
Define Nonspontaneous
It is the very of Spontaneous reactions, due to the fact that it needs continuous input of energy
A system going from an ordered state to a disorderly system has entropy that is _________ and is considered a _____________ reaction
Increasing; spontaneous
What is the equation used for Entropy?
ΔS = S final - S initial
Spontaneous ΔS…
ΔS > 0 (positive value)
Nonspontaneous ΔS…
ΔS < 0 (negative value)
At equilibrium ΔS…
ΔS = 0
of microstate __________ means _______ disorderly and S __________
Increases; more; increases
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
From solid to liquid to gas, Entropy ΔS __________
Increases
What is the equation relating Entropy and system exchanging of heat
ΔS = Qrev / T
What is the process from a Gas to a Liquid phase?
Condensation
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
