Studied by 1 personWhat is the second law of thermodynamics?
heat always moves from hotter objects to cooler objects, unless energy is supplied to cause the reverse to occur
for any spontaneous process the entropy of the universe must always increase
What is a spontaneous process?
a process that occurs on its own (does not refer to the rate of reaction)
What determines the direction of a spontaneous process?
the entropy change
What is entropy?
the dispersal of matter and energy (sometimes defined as a measure of the “disorder”)
At equilibrium entropy of the universe must be _________, and change in entropy of the universe must be ___.
at a maximum
0
Entropy is a _______ function and is ___________, meaning that it depends on _________________.
state
extensive
the amount of substance
What is the 2nd law of thermodynamics?
For any spontaneous process the entropy of the universe must always increase (change always occurs in the direction of maximal probability).
How does volume change of a gas affect entropy?
entropy increases with volume because there are more possible positions for each particle (disorder increases)
How does temperature change affect entropy?
entropy increases with temperature because there are more possible energies for each particle (disorder increases)
Since S increases with T, this implies that in an exothermic reaction heat flows ________ of the system and the entropy of the surroundings _____________.
out
increases
In which phase is entropy the lowest? In which phase is entropy the highest?
lowest → solid (most ordered)
highest → gas (most disordered)
How does mixing of gases affect entropy?
gases always mix, so entropy will always increase with mixing
How does number of moles affect entropy?
increasing the number of moles increases entropy
What is the 3rd law of thermodynamics?
The entropy of a perfect crystalline solid at 0 K is defined to be 0 J/K
What is standard entropy?
The entropy of 1 mole of a substance at standard state conditions
At constant temperature and pressure, delta G equals?
delta G = delta H - T * delta S
If delta G is negative, the forward process is ____________
spontaneous
If delta G is positive, the forward process is _____________
non-spontaneous
If delta G is 0, the process is _____________
at equilibrium
What does delta G represent?
the maximum energy available to do work
A system at equilibrium can do no ________
work
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What does exergonic mean? What does endergonic mean?
exergonic → -delta G
endergonic → +delta G
For a system at equilibrium at constant temperature and pressure delta G equals ____
0
What are standard free energies of formation?
the value for the formation of 1 mole of a substance from the most stable forms of its elements
At standard state conditions, if free energy change is less than 0, K is ____________
greater than 1
At standard state conditions, if free energy change is greater than 0, K is ___________
less than 1
At non-standard state conditions, if free energy change is less than 0, then Q is ________ than K and the reaction is ______________
less
spontaneous
At non-standard state conditions, if free energy change is greater than 0, then Q is ________ than K and the reaction is ______________
greater
non-spontaneous
Note
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