Why you should understand Entropy:
Entropy is one way that chemists can show how atoms and molecules behave. Entropy takes into account how molecules move around and how often they bump into each other. When chemists are trying to figure out how likely a reaction is to occur, entropy is a very important factor to consider.
Key Concepts
- Defining Entropy
- Microstates
- The relationship between Microstates, energy, and entropy
- Boltzmann Formula
Defining Entropy
Entropy can be described as the amount of disorder in an enclosed space. However, Entropy is better described as the possibility for a space to be disordered. What does this mean? There is a certain probability that describes the likelihood of a molecule or atom being in a certain location at a certain time. The likelihood that a molecule is in a certain location with a specific orientation and energy is a better definition of Entropy.
Entropy increases under the following conditions:
1. The state of matter changes from more disordered to less disordered.
Solids are considered the most ordered state of matter. This means they have the least amount of entropy. Liquids are less ordered than solids and gases are less ordered than liquids. This means that Gases have the most entropy when comparing states of matter.
2. The number of molecules or atoms increases.
The fewer number of molecules which are present in a container, then the lower the entropy. As the number of molecules increases, the entropy also increases. The more molecules there are, the more possible arrangements of the molecules there can be. This is related to microstates.
3. The number of microstates increases.
I'll define microstates below, but the general trend is that as the number of microstates increases the entropy increases.
Microstates
Microstates are the number of possible orientations and amounts of energy a mixture of molecules can have.
If I took a snapshot of a container that had molecules bouncing around, the snapshot would represent a microstate for each individual molecule. Each molecule in the snapshot has a certain amount of energy and orientation at the exact moment I take the picture. The number of possible orientations and amounts of energy represents the number of possible microstates for each molecule.
The Relationship between Microstates, Energy, and Entropy
As Energy is increased (perhaps by heating up the container) the number of microstates increases. This is because temperature adds energy to the molecule which can then be transferred through collisions.
As the number of microstates increases the Entropy increases. This means that an increase in energy also increases Entropy.
Boltzmann Formula
The formula below is called the Boltzmann formula. This formula takes microstates into account when calculating Entropy.
The Boltzmann formula is just one of many formulas that can be used to calculate Entropy.
Summary
- Entropy can be described as the amount of disorder in an enclosed space. However, Entropy is better described as the possibility for a space to be disordered.
- Entropy increases when the state of matter changes from more disordered to less disordered, the number of molecules increases, or the number of microstates increases
- Microstates are the number of possible orientations and amounts of energy a mixture of molecules can have.
- The Boltzmann formula takes microstates into account when calculating Entropy.
I hope this post about Entropy has been helpful. Feel free to leave a comment below or message me if you have any questions. I've also attached my Youtube video lesson about Entropy below.
- Saren
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