A high entropy system is often described as a system in which thier is a lot of disorder, akin to a teenagers bedroom. An illustration often used by chemistry teachers teaching A-level, advanced higher or IB chemistry. This is more or less an appropriate way of explaining entropy. However a more rigorous explaination would be to use statistical thermodynamics and expalain Boltzmann's famous equation etched on his grave.
S=klnW
S is entropy, K is the Boltzmann constant and W is the number of microstates (calculated using a statistical approach)
What this equation shows is that entropy can be more accurately described as the probability distribution of energy states of a system at equilibrium. The greater the entropy the greater this distribution.
This fits nicely into the second law of thermodynamics "things tend to disorder". Entropy therefore tends to increase. Does this mean mess and more mess? If it did the world around us would just get messier and messier but it doesn't.
When a living organism dies it gets recyled, it gets torn apart by bacteria etc and taken back into the environment to get re-used. This is an increase in entropy. Without entropy our earth would soon get clogged up with non composing dead things, our earth would soon be uninhabitable.
Beautiful well ordered low entropy crystals, cause an increase in the entropy from the solution they come from (as the crystals crash out of the solution, molecules/ions in the solution have more freedom to move about ie they have a greater entropy), this apparent decrease in entropy is not breaking the second law of thermodynamics as entropy overall has increased. This has been used to explain order from chaos such as the formation of planets and stars.
Entropy is messy but it is also necessary for the continuation of life. Studying entropy change is also useful in chemistry to calculate if a reaction is thermodynamically possible. This leads us to the famous Gibbs free energy equation. When the Gibbs free energy is negative the reaction is thermodynamically possible.
ΔG=ΔH−TΔS
ΔG change in free energy ie the energy available to do work.
ΔH change in enthalpy (a topic for a future blog)
TΔS temperature in Kelvin multiplied by change in entropy
It is the conclusion of this article that entropy is messy, but without mess we could never get order. Without entropy life could not be sustained.
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