Where can we apply the first law of thermodynamics?

In summary, the first law of thermodynamics is applicable between all equilibrium points as it is a formulation of the conservation of energy. However, when studying equilibrium thermodynamics, it is more common to apply it at the different points where the system is in equilibrium. The process of free expansion of a gas into vacuum is an example where the first law is applied between the final and initial equilibrium points, resulting in a change in internal energy of 0.
  • #1
kulkajinkya
12
1
Hi people, I have a question. Where can we apply the first law of thermodynamics? I mean is it applicable between 2 equilibrium points? Or between a reversible process?
When we consider free expansion of a gas into vacuum, we apply the first law. But since the process isn't reversible (or even defined), we apply it between the final and initial equilibrium points and hence conclude ΔU=0.
So my question is is it applicable between 2 equilibrium points, for a reversible process, or for a general irreversible/reversible process?
 
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  • #2
The first law of thermodynamics is just a particular formulation of the conservation of energy. Therefore, it applies at all times. It's just that separating energy into work and heat, which you do in thermodynamics, can be difficult for transient processes. When studying equilibrium thermodynamics, it is more common to apply it at the different points where the system is in equilibrium.
 

1. What is the first law of thermodynamics?

The first law of thermodynamics, also known as the law of conservation of energy, states that energy cannot be created or destroyed, only transferred or converted from one form to another.

2. Where can we apply the first law of thermodynamics?

The first law of thermodynamics can be applied to any system that involves energy, such as chemical reactions, heat engines, and thermal processes.

3. How does the first law of thermodynamics relate to the concept of work?

The first law of thermodynamics states that the change in internal energy of a system is equal to the heat added to the system minus the work done by the system. This means that work is a form of energy transfer and is included in the calculation of the system's total energy.

4. Can the first law of thermodynamics be violated?

No, the first law of thermodynamics is a fundamental law of nature and has been proven through numerous experiments. Energy can neither be created nor destroyed, so it cannot be violated.

5. What are some practical applications of the first law of thermodynamics?

The first law of thermodynamics has many practical applications, including the design of energy-efficient buildings, the development of renewable energy sources, and the optimization of industrial processes to reduce energy waste.

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