Internal energy of a system is the
- A. heat supplied to the system only
- B. work done by the system only
- C. total of all kinetic and potential energies of the particles in the system
- D. energy lost to the surroundings
Explanation
Internal energy sums the translational, rotational and vibrational energy of the particles together with the potential energy stored in the bonds and intermolecular forces. Its absolute value cannot be measured, but the change in it can, which is all thermodynamics requires. It is a state function, so the change depends only on the initial and final conditions.