CHEM 112 Lecture Notes - Lecture 25: Calorimeter

• School: Queen's University
• Department: Chemistry
• Course: CHEM 112
• Professor: Richard Oleschuk

Document Summary

Path dependent functions: changes in heat and work are not functions of state. We live in a constant pressure world, but not a constant volume world. A system at constant volume is a bomb calorimeter. Enthalpy (h) is all of the state functions. Enthalpy states the first law of thermodynamics in a constant pressure situation. If pistons are holding the stopper thing, there is constant pressure and volume, if pistons are not holding the stopper than work can be done, if work is being done on something then there is positive work. The work is not a big deal most of the time, the heat of the reaction is what is important (internal energy) so work doesn"t matter because it is small. Endothermic and exothermic reactions: when delta h is negative heat is being released so it is exothermic, when it is positive it is endothermic, and it is gaining heat.