Thermodynamics- validity of change of internal energy equation

In summary, the internal energy equation in thermodynamics is the first law of thermodynamics, which states that the change in internal energy (ΔU) of a system is equal to the heat (Q) added to the system minus the work (W) done by the system. It is valid for all thermodynamic processes and is derived from the principle of conservation of energy. It can also be applied to open systems, but may need to be modified in cases of phase changes or chemical reactions.
  • #1
mjki9ec3
3
0
Just had a thermodynamics exam, and one of the questions was

For an ideal gas, is the relation [tex]\Delta[/tex]U = mC[tex]_{}v[/tex][tex]\Delta[/tex]T restricted to constant volume processes only? Why?

I wrote that it was only valid for constant volume processes, because this is what C[tex]_{}V[/tex] is defined as, however now I'm starting to think that is only true for Q, and that equation is true for any process, not just constant volume.

thanks in advance!
 
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  • #2
oops, meant to be subscript v's obviously :)
 

Related to Thermodynamics- validity of change of internal energy equation

What is the internal energy equation in thermodynamics?

The internal energy equation in thermodynamics is the first law of thermodynamics, which states that the change in internal energy (ΔU) of a system is equal to the heat (Q) added to the system minus the work (W) done by the system. Mathematically, it can be represented as ΔU = Q - W.

Is the internal energy equation valid for all thermodynamic processes?

Yes, the internal energy equation is valid for all thermodynamic processes. This is because it is a fundamental law of thermodynamics and applies to all closed systems.

How is the internal energy equation derived?

The internal energy equation is derived from the first law of thermodynamics, which is based on the principle of conservation of energy. It can also be derived from the concept of energy balance, where the change in internal energy is equal to the sum of the heat and work exchanged with the surroundings.

Can the internal energy equation be applied to open systems?

Yes, the internal energy equation can also be applied to open systems, where there is exchange of matter and energy with the surroundings. In such cases, the equation is modified to include the change in enthalpy (H) of the system, and is represented as ΔH = Q - W + ΔU.

What are the limitations of the internal energy equation?

The internal energy equation has limitations when applied to systems undergoing phase changes or chemical reactions, as it does not take into account the change in potential energy. In such cases, the equation needs to be modified to include the change in chemical potential energy and/or latent heat.

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