Editing Thermochemistry (section)

==Systems==
Several thermodynamic definitions are very useful in thermochemistry. A system is the specific portion of the universe that is being studied. Everything outside the system is considered the surroundings or environment. A system may be:
* a (completely) [[isolated system]] which can exchange neither energy nor matter with the surroundings, such as an insulated [[bomb calorimeter]]
* a [[thermally isolated system]] which can exchange mechanical work but not heat or matter, such as an insulated closed [[piston]] or [[balloon]]
* a [[mechanically isolated system]] which can exchange heat but not mechanical work or matter, such as an '''un'''insulated [[bomb calorimeter]]
* a [[closed system]] which can exchange energy but not matter, such as an '''un'''insulated closed piston or balloon
* an [[Thermodynamic system#Open system|open system]] which it can exchange both matter and energy with the surroundings, such as a pot of boiling water