Spontaneous: proceed without any external influence
Nonspontaneous: needs an external influence to occur
A spontaneous process will drive towards equilibrium
These can be fast or slow. We are not talking about kinetics here, that was chapter 14. This is just us talking about IF it will happen, not the speed at which it will.
We are speaking about what is thermodynamically favorable
Enthalpy and Entropy
When we think about enthalpy, we can have a negative delta H function, exothermic and feels hot, or a positive delta H function, endothermic and feels cold.
Entropy is delta S. This is disorder/randomness (easiest way to call it, but it is the cheap and easy way)
The number of ways a system can be arranged
Boltzmann's Equation: $S = k\times lnW$
W is the number of ways that a state can be achieved
First law of thermodynamics
The total energy in the system and surrounds is constant
Second law of thermodynamics
The total entropy in the system and its surroundings will always increase for a spontaneous process
Entropy Changes
Entropy and temperature
As temperature increases, entropy increases
The entropy of a pure substance at 0K will be zero
There will be a steady increase in entropy with an increase in temperature, punctuated by discontinuous jumps at phase transitions
Entropy and state changes
Very large increase in entropy as we go from liquid to gas, with a large, but smaller, increase from solid to liquid
Very large decrease in entropy as we go from gas to liquid, with a large, but smaller, decrease from liquid to solid
Molecularity
The change in the number of particles
As molecularity increases, entropy increases as well
Entropy and state changes calculation
$\Delta S = \frac{Z_{rev}}{T}$
Entropy will have units of J/k
Heat transfer and energy changes of the surroundings
delta S of the university is equal to delta S of the system plus delta S of the surroundings
If you have an exothermic reaction, heat is going to go from the system to the surroundings
Positive delta S
If you have an endothermic reaction, heat will go from the surroundings to the system
Negative delta S
Spontaneous reactions have a delta S of the universe being greater than zero
Nonspontaneous reactions have a delta S of the universe being less than zero
At equilibrium, delta S of the universe is equal to zero
Temperature dependence of delta S of the surroundings
At higher temperatures, we see less change in delta S of the surroundings
At lower temperatures, we see more change in delta S of the surroundings
This is because it is a more meaningful change in energy
We can quantify entropy changes in the surroundings
delta S of the surroundings is equal to negative delta H of the system over T. This works at a constant P and T
