Core
Energetics: Enthalpy
Slide 22 of 34
System and Surrounding
In the
study of thermochemistry or energetics (and also chemical equilibrium),
the region or particular quantity of matter of interest—the portion
we single out for study—must first be defined.
If
transfer of energy is to be considered, one must be able to state where it
is flowing from (what the source is) and what it is
flowing into (what the sink is), for example.
–Since energy is
conserved, any observed change is just the flow of energy from one
to another.
With
chemical systems, the energy flow is between a system
and the surrounding.
The region
that is singled out for study is defined as the system
and everything else as the surrounding.