what is meant by the internal energy of a gas.?
1) The internal energy of a gas is the total kinetic energy of the constituent atoms or molecules due to their motion. This may contain contributions from translation, rotation and vibration, where appropriate. 2) The internal energy of a monatomic gas depends only upon the kinetic energy of the translational energy of the atoms, while that for diatomic gases includes rotational and vibrational components. Using the techniques of statistical mechanics, it is possible to show that each degree of freedom ideally should contribute 0.5 k T to the total internal energy. For a monatomic gas there are 3 degrees of freedom corresponding to translational motion in the three spatial dimensions, giving a total of 1.5 k T. In the case of diatomic gases, two additional degrees of freedom are available, corresponding to rotational and vibrational motion of the molecule, increasing the total to 2.5 k T. 3) Macroscopic variables are those of the system or material under consideration as a whole eg tem
