In an Isolated system, neither energy nor masses are permitted to cross the boundary. The system has constant mass and energy. No such system exists physically. Universe is the only example that is perfectly isolated system. Other Special System
1. Adiabatic System: A system with adiabatic walls can only exchange work and not heat with the surrounding. All adiabatic systems are insulated thermally from their surroundings.
The example is Thermos flask containing a liquid.
2. Homogeneous System: A system that consists of a single phase is called as homogeneous system. For example, the mixture of air and water vapour, water added to nitric acid and octane added to heptanes.
3. Hetrogeneous System: A system, which comprises of two or more phase, is called as heterogeneous system. Example of it is Water added to steam, Ice added to water and water added to oil.