# Thermodynamics

Contents

Heat can be useful, but it can also be annoying. Understanding heat and the flow of heat allows us to build heat sinks that prevent our computers from overheating, build better engines, and prevent freeway overpasses from cracking.

## Temperature, kinetic theory, and the ideal gas law

In these videos and articles you'll learn about the Celsius and Kelvin temperature scales. The definition of a mole of a substance will be given. You'll also learn how the ideal gas law relates the pressure, volume, and temperature of a gas. Lastly, you'll learn how the Maxwell-Boltzmann distribution gives the probability of finding a gas molecule moving at a specific speed.

9:49

Thermodynamics part 1: Molecular theory of gases

Intuition of how gases generate pressure in a container and why pressure x volume is proportional to the combined kinetic energy of the molecules in the volume.

10:17

Thermodynamics part 2: Ideal gas law

To begin, Sal solves a constant temperature problem using PV=PV. Then he relates temperature to kinetic energy of a gas. In the second half of the video, he derives the ideal gas law.

10:24

Thermodynamics part 3: Kelvin scale and Ideal gas law example

Sal makes the case for the Kelvin scale of temperature and absolute zero by showing that temperature is proportional to kinetic energy. Then he explains that you need to use the Kelvin scale in the ideal gas law. To finish he does a sample ideal gas law problem.

10:14

Thermodynamics part 4: Moles and the ideal gas law

Sal explains the concept of a mole. Then he derives the molar version of the ideal gas law PV=nRT, where the gas constant R=831 J/molK.

8:02

Thermodynamics part 5: Molar ideal gas law problem

Sal uses the molar version of the ideal gas law to solve for the number of moles in a gas. He also shows how to convert this answer into number of molecules using Avogadro's number.

Article

What is the ideal gas law?

Learn how pressure, volume, temperature, and the amount of a gas are related to each other.

9:30

Maxwell Boltzmann distribution

Using the Maxwell-Boltzmann distribution to visualize the distribution of speeds of particles at different temperatures.

Article

What is the Maxwell-Boltzmann distribution?

In a gas, there are lots of molecules traveling at lots of different speeds. Here's a framework for thinking about that.

## Specific heat and heat transfer

In these videos and articles you'll learn the definition of specific heat and latent heat and how to use them in problem solving. You'll also learn the 3 modes of heat transfer; conduction, convection, and radiation. Lastly, we will look in more depth at how the rate of thermal conduction through a material depends on the material's thickness, conductivity constant, area, and difference in temperature.

14:57

Specific heat and latent heat of fusion and vaporization

Defining specific heat, heat of fusion, and heat of vaporization. How to calculate the amount of heat to change the temperature of water and the energy required to change for a phase change.

9:10

Thermal conduction, convection, and radiation

Fire as thermal conduction, convection, and radiation

7:16

Thermal conduction

Intuition behind how heat gets transferred through thermal conduction.

7:22

Thermal conductivity of metal and wood

Why metal at room temperature feels cooler than wood at room temperature.

6:18

Intuition behind formula for thermal conductivity

Intuition behind formula for thermal conductivity

Article

What is thermal conductivity?

Read this article to learn how to determine the rate at which heat conducts through a material.

## Laws of thermodynamics

In these videos and articles you'll learn how the first law of thermodynamics relates the change in internal energy of a gas, heat that enters the gas, and work done on the gas. PV diagrams will be discussed, as well as the four common thermal process; isobaric, isochoric/isovolumetric, isothermal, and isovolumetric processes.
You'll also learn about how the second law of thermodynamics relates the entropy change to the multiplicity of microstates and the heat that enters a macroscopic system. The efficiency of a heat engine will also be explained.

18:29

Macrostates and microstates

The difference between macrostates and microstates. Thermodynamic equilibrium.

14:37

Quasistatic and reversible processes

Using theoretically quasi-static and/or reversible processes to stay pretty much at equilibrium.

17:40

First law of thermodynamics / internal energy

First law of thermodynamic and internal energy

13:45

More on internal energy

Getting more intuition of internal energy, heat, and work. Examples of using the first law to calculate work.

Article

What is the first law of thermodynamics?

Learn what the first law of thermodynamics is and how to use it.

12:43

Work from expansion

How a system can do work by expanding

15:24

PV-diagrams and expansion work

Why work from expansion is the area under the curve of a PV-diagram. Why heat is not a state function and internal energy is a state function.

Article

What are PV diagrams?

Learn what PV diagrams are and how to use them to find the change in internal energy, work done, and heat.

16:56

Proof: U = (3/2)PV or U = (3/2)nRT

Conceptual proof that the internal energy of an ideal gas system is 3/2 PV.

19:03

Work done by isothermic process

Isothermic and adiabatic processes. Calculating the work done by an isothermic process and seeing that it is the same as the heat added.

20:53

Carnot cycle and Carnot engine

Introduction to the Carnot cycle and Carnot heat engine

17:08

Proof: Volume ratios in a carnot cycle

Proof of the volume ratios in a Carnot cycle

15:38

Proof: S (or entropy) is a valid state variable

Proof that S (or entropy) is a valid state variable.

15:38

Thermodynamic entropy definition clarification

Clarifying that the thermodynamic definition of Entropy requires a reversible system.

28:26

Reconciling thermodynamic and state definitions of entropy

Long video explaining why entropy is a measure of the number of states a system can take on (mathy, but mind-blowing).

19:15

Entropy intuition

Introduces second law of thermodynamics. A discussion of entropy change in terms of heat and microstates .

13:27

Maxwell's demon

Maxwell's Demon: A thought experiment that seems to defy the 2nd Law of Thermodynamics

8:56

More on entropy

Distinguishing between microstates and macro states. How entropy S is defined for a system and not for a specific microstate.

14:04

Efficiency of a Carnot engine

Definition of efficiency for a heat engine. Efficiency of a Carnot Engine.

14:01

Carnot efficiency 2: Reversing the cycle

Seeing how we can scale and or reverse a Carnot Engine (to make a refrigerator)

12:17

Carnot efficiency 3: Proving that it is the most efficient

Proving that a Carnot Engine is the most efficient engine