Spontaneity and Entropy
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37 Terms
A spontaneous process is…
one that occurs without outside intervention
Spontaneous processes can relaese…
energy, require energy, or involve no energy change at all
Spontaneity is independent of…
the speed or rate of a reaction. A spontaneous process may proceed very slowly
Chemical kinetics focuses on the…
pathway between reactants and products
The kinetics of a reaction depends on…
activation energy, temperature, concentration, and catalysts
thermodynamics only considers…
the initial and final states
To describe a reaction fully…
both kinetics and thermodynamics are necessary
If enthalpy is negative, than it is
exothermic, b/c heat is being lost
Three factors that combine to predict spontaneity
energy change
temperature (change of H)
entropy change
What combines the tree factors to predict the spontaneity of a process?
The Gibbs Free Energy (G)
If delta G is less than 0…
it is a spontaneous reaction
The first law of thermodynamics is…
The energy of the universe is constant, but the various forms of energy can be interchanged in physical and chemical processes
Entropy
a measure of the disorder of a system
In general, greater disorder means
greater entropy
The natural tendency of entropy is…
towards disorder
Boltzmann equation
S = k ln W
What is k?
The Boltzmann constant
What is W
the number of energetically equivalent ways to arrange the components of the system
Gases will spontaneously and uniformly mix because…
the mixed state has more possible arrangements than the unmixed state
The driving force for a spontaneous process is an…
increase in the entropy of the universe
Gases have more…
entropy than liquids or solids
mixtures have more…
entropy than a pure substance
The 2nd law of thermodynamics
in any spontaneous process there is always an increase in the entropy of the universe
Probability
What is the chance that the order of the cards can be restored by reshuffling, negative deltaS
microstates
possible distributions
entropy of a system is related to…
the natural log of the number of microstates
entropy is what kind of function?
a state function
Standard entropy
absolute entropy of a substance at 1 atm
entropy for gase phase is greater than that of…
liquid or solid of same substance
more complex structures…
have greater entropy
allotropes, in terms of entropy
more ordered forms have lower entropy
Anything that increases number of microstates has…
a greater entropy
Entropy of the universe increases in a…
spontaneous process and remains unchanged in an equilibrium process
Equilibrium process:
caused to occur by adding or removing energy from a system that is at equilibrium
The 3rd law of thermodynamics
A perfect crystal at absolute zero has an entropy value (S) of ). All other substances have positive values of entropy due to some degree of disorder
change in entropy of surroundings is directly…
proportional to the enthalpy of the system
exothermic process corresponds to…
positive entropy change in surroundings