Chapter 17 Flashcards
What is the driving force for a spontaneous process?
Increase in entropy of the universe
In any spontaneous process there is always?
An increase in entropy of the universe
Entropy changes in the surroundings are primarily determined by?
heat flow
the impact of heat transferring from the surroundings will be greater at?
lower temperatures
A process at constant temperature and pressure is spontaneous only when?
ΔG is negative
When a reaction involves gaseous molecules, the change in positional entropy is dominated by?
the number of molecules of products and reactants.
gaseous products > gaseous reactants.
positional entropy______
ΔS is _______
positional entropy increases
ΔS is positive
gaseous products < gaseous reactants.
positional entropy______
ΔS is _______
positional entropy decreases
ΔS is negative
the equilibrium position represents what?
the lowest free energy value available to a reaction system.
The maximum amount of useful work is equal to?
ΔG (change in free energy)
Achieving maximum work can only be achieved via hypothetical pathway because?
Any real pathways waste energy.
In any real cyclic process (beginning and end have same result) in the system work is changed to what and where?
heat in the surroundings
In any real cyclic process in the system, the entropy of the universe?
increases
As we use energy what happens?
we degrade its usefulness
What does 1st law of thermodynamic not tell us?
Why something happens in the direction it does
in thermodynamics entropy tells us?
the # of arrangements or micro states in a system
positional entropy
the probability of a particular state depending on number of ways arrangement can be obtained
the entropy of the universe is increasing but energy is?
constant
for anything to be spontaneous the entropy of the universe must be?
positive
ΔS universe +
Entropy _____
Process is _____
increasing
spontaneous
ΔS universe -
Entropy ______
Process is _____
decreasing
non-spontaneous in desired direction
ΔS is 0
equilibrium is reached
Magnitude of ΔS surroundings is dependent on?
temperature
Exothermic
ΔS surr _____
ΔS universe ____
+,-
Endothermic
ΔS surr _____
ΔS universe ____
-
+
ΔH -
TΔS +
ΔG?
-
(spontaneous)
ΔH?
TΔS +
ΔG -
-
ΔH -
TΔS?
ΔG -
+
ΔH-
TΔS -
ΔG?
spontaneous if ΔH is greater than TΔS (low temperature)
ΔH +
TΔS +
ΔG?
spontaneous if TΔS is greater than ΔH (high temperature)
ΔH +
TΔS -
ΔG?
+ (non- spontaneous)
Third law of thermodynamics
The entropy of a perfect crystal at 0K is zero
What is the main idea behind the third law of thermodynamics?
there is absolute order/ no disorder since everything is in perfect position.
the more negative ΔG value,what direction does the reaction shift?
to the right to achieve equilibrium
Entropy depends on what?
volume and pressure
K= 1
equilibrium
K<1,where does reaction shift?
shift to left
K >1
shift to right
if shifting to the left it is _____ favored?
reactant
If shifting to the right it is ______ favored?
product
Equilibrium is not always ____ for thermodynamics?
half & half
If ΔG is zero it means?
free energy of products and reactants are equal
ΔG < 0, then k is?
> 1
ΔG > 0, then k is?
<1
if k is 1 then pressure is?
1 atm
If ΔG is <0, it meanswhat about standard energy?
standard energy of the products is less than the standard energy of the reactants
Since products has less free energy the shift must be?
right (product favored)
ΔG < 0
product pressure _____
reactant pressure ____
greater than 1atm
less than 1 atm
If reactants have lower free energy, then shift must be?
left (reactant favored)
equilibrium shifts from?
high energy to low energy
ΔG > 0
reactant pressure _____
product pressure ______
> 1 atm
< 1 atm
Free energy
energy available to do work
