First Law of Thermodynamics-Conservation of Energy . The change in the internal energy of a system is the sum of the amount of energy it gains as heat plus the energy it gains from having work done on it. Second Law of Thermodynamics-Entropy 3. Third Law of Thermodynamics-Absolute K C. Spontaneous Changes and Reversibility 1. Two fundamental laws of nature - a. Systems tend toward a state of lower energy.
Systems tend toward a state of maximum disorder.
One or both of the above accompanies a spontaneous change. When a change lowers the energy of a system, the change tends to be spontaneous. There is only one reversible path between any 2 states of a system. Irreversible change-the system cannot be exactly restored by simply reversing the change. Rusting of a nail.