Enthalpy calorimetry and

Enthalpy is a state function. A change in enthalpy does not depend on the pathway between two states. 

Recall from the previous section that w and PA 1/have opposite signs  

The change in enthalpy of a system has no easily interpreted meaning except at constant pressure, where AW = heat. 

At constant pressure, exothermic means AW is negative endothermic means AW is positive. 

So far we have discussed the internal energy of a system. A less familiar property of a system is its enthalpy H, which is defined as 

Unless otherwise noted, all art on this page is ) Cengage Learning 2014. 

---