Hello Everyone! Welcome back to Teach Me to Science. This is the written version of my introductory lesson on Thermodynamics.
Thermodynamics is a difficult subject in general chemistry 2. Typically the first half of general chemistry 2 is completely dedicated to Thermodynamics, which is why it's very important to understand the subject to the best of your ability. In addition to this written lesson, I have a video lesson on the basics of thermodynamics which I'll link below.
Sometimes it's helpful to break down a word into its parts to better understand its meaning. Thermodynamics is an excellent example of this. Thermo, means relating to temperature or heat. Dynamics, when I think of dynamics I think of something that's complicated or has a lot of pieces. I also think of movement when I hear the word dynamics. Putting together these simpler definitions gives us a good idea of what Thermodynamics might be about; the movement of heat or thermal energy.
Thermodynamics is a huge part of General Chemistry 2 and has lots of parts to it including: enthalpy, entropy, exothermic reactions, endothermic reactions, spontaneity, gibbs free energy, the first law of thermodynamics, the second law of thermodynamics, the third law of thermodynamics, gibb's free energy, hess' law, exergonic reaction, endergonic reactions, specific heat, and state functions. Just to name a few (or all of them).
For now, don't worry too much about all these different sub topics of thermodynamics. Right now we are thinking big picture.
Thermodynamics explains the movement of heat energy from place to place. This means when it's finished you'll be able to explain why an ice cube melts at room temperature! (cool right?)
To set the framework for the thermodynamics unit, there are a few key terms you need to know and understand. They are work, energy, and heat.
Work is energy required to change an objects position and is associated with movement.
For example, I'm trying to push my couch across the floor. If I successfully move the couch, then I've done work. If I struggle and try to push the couch but it doesn't go anywhere, then I haven't done any work.
Energy is the ability to do work. I know this seems backwards because the definition of work relies on energy. And if the definitions rely on one another then its kinda of a circular scenario. Like which came first, the chicken or the egg? Which comes first, work or energy?
Rather than confusing ourselves (or maybe I already have), lets take a step back and simplify the definition of energy. Rather than the ability to do work, lets think of energy as the ability to do something. For example, it takes energy for me to heat up my coffee. So heat energy could be characterized by an ability to increase or decrease temperature. Like wise chemical energy (which is energy exchanged by chemical reactions) could be considered by the ability to form a product in a chemical reaction. When you think of energy in this way, its less confusing and doesn't hurt my head as much.
It turns out that there are multiple kinds of energy, such as: chemical, potential, kinetic, light, and nuclear. Kinetic energy is associated with movement. Potential energy is typically a change in height. Light energy comes from wavelengths of particles which we see as light. Chemical energy is the energy associated with chemical reactions. Nuclear energy is the energy created using nuclear chemistry.
And now lets define heat. Heat is typically thought of as hot, cold, or a change in temperature. Reminder, the feeling of "cold" is actually an absence of heat. Cold is not a measurable entity itself. For example, a thermometer doesn't measure hold cold it is, it measures how much heat is present. If there isn't very much heat present, then we consider it to be cold.
The final thing we need to define in the system and the surroundings. To be able to track the movement of heat from one area to the next, we need a way to easily describe the locations of the heat. The system and surroundings help with that. The system is the area of interest. The surroundings is everything around the system.
Consider this if I put a hot coffee in the freezer, will my hot coffee cool down or heat up? While the answer may seem simple, it also is a great example of system and surroundings. My question asks what will happen to my hot coffee in the freezer. I'm interested in the temperature change of my coffee. This means my coffee is my object of interest and is my system. The freezer is enclosing my coffee cup, which means that my freezer is the surroundings.
Note: I could have phrased this differently which would have made the freezer my system and the coffee the surroundings. What would that look like?
I hope you've found this introduction to thermodynamics helpful. Please watch the video above for more information and leave a comment on either this post or the video If you have questions.
Saren
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