Thermodynamics MOC

First Law of Thermodynamics

The first law is a statement of Conservation of energy in a thermodynamic system.

The change of internal energy of a system is the sum of the Heat added to and Work done on the system, and depends only on the initial and final states of the system and not on the particular process involved.

For any infinitesimal process on a Thermodynamic system the change in internal energy is given by¹

where

• is the infinitesimal heat added to the system;
• is the infinitesimal work done on the system;
• is the chemical potential of species ; and
• is the infinitesimal change in the number of particles of species .

In the case of a Quasistatic process, the Quasistatic expression for work and definition of Entropy give

Special cases

• First law for isovolumetric processes
• First law for isobaric processes
• First law for isothermal processes

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Footnotes

1. Here we use the IUPAC signing convention. ↩