Entropy: Joules per Kelvin Explained

  • Thread starter Thread starter Saado
  • Start date Start date
  • Tags Tags
    Entropy Principle
AI Thread Summary
Entropy is defined as a measure of the number of ways a system can be arranged, but its units of joules per kelvin can be confusing. This unit reflects the relationship between energy transferred into a system and the absolute temperature of that system, as dictated by the second law of thermodynamics. The discussion highlights that energy represents the heat added, while temperature indicates the system's state in Kelvin. The interpretation of entropy as a measure of "disorder" is considered misleading by some, emphasizing the need for clarity in understanding its implications. Overall, the connection between energy, temperature, and entropy is crucial for comprehending thermodynamic processes.
Saado
Messages
44
Reaction score
0
Whilst I understand that entropy is a measure of the number of specific ways in which a system may be arranged. The units for entropy don't make sense to me intuitively. Why joules per kelvin? What way at all does that show how "disordered" a system is. When I hear joules per kelvin, I think of energy/average thermal energy.

What does the energy and temperature represent in this case?
 
Science news on Phys.org
You can transform it to a dimensionless value with the Boltzmann constant. And that is just a unit conversion factor.
 
Saado said:
What way at all does that show how "disordered" a system is.
Here is a nice video on why the "disorder" interpretation of entropy is misleading:



More links in the video description on youtube.
 
Why joules per kelvin?
It follows from the second law of thermodynamics.
What does the energy and temperature represent in this case?
It is the change of entropy. In this case, energy is the heat transferred into the system and temperature is the absolute temperature (in Kelvin) the system at.
 
td21 said:
Why joules per kelvin?
It follows from the second law of thermodynamics.
What does the energy and temperature represent in this case?
It is the change of entropy. In this case, energy is the heat transferred into the system and temperature is the absolute temperature (in Kelvin) the system at.

So the temperature is the absolute temperature before the heat energy is transferred into the system?
 
I need to calculate the amount of water condensed from a DX cooling coil per hour given the size of the expansion coil (the total condensing surface area), the incoming air temperature, the amount of air flow from the fan, the BTU capacity of the compressor and the incoming air humidity. There are lots of condenser calculators around but they all need the air flow and incoming and outgoing humidity and then give a total volume of condensed water but I need more than that. The size of the...
Thread 'Why work is PdV and not (P+dP)dV in an isothermal process?'
Let's say we have a cylinder of volume V1 with a frictionless movable piston and some gas trapped inside with pressure P1 and temperature T1. On top of the piston lay some small pebbles that add weight and essentially create the pressure P1. Also the system is inside a reservoir of water that keeps its temperature constant at T1. The system is in equilibrium at V1, P1, T1. Now let's say i put another very small pebble on top of the piston (0,00001kg) and after some seconds the system...

Similar threads

Back
Top