Free Energy and Work
The reason for doing all of this
work is so it can work for us. Looking at these processes
we can find whick can do work the most efficient and
economical. Finding whether something is spontaneous it can
prevent us from wasting effort on a process that has no inherent
tendency to occur. Some reaction may be slow and we will
have to find a catalyst that will speed it up. The free
energy can tell us how much work can be done by a process.
The maximum of possible work is equal to the change in free
energy: wmax = 
G. This is why it is called free energy. G represents the energy that is free to do
work. The amount of work from a process will always be less
than the maximum possible amount. Like in a car engine,
when we calculate the G for the
battery reaction it isn't the real amount of work because some
energy is lost through the electricity traveling through the
wires. Achieving maximum work can only be done by a
hypothetical pathway. There are also reversible
process. It is like recharging a battery. When a
battery is all drained then it is a irreversible process.
All processes are irreversible.
