Fig. 1.1, Van Holde, Principles of physical biochemistry, Prentice ...

Reversible and irreversible processes differ in their
pathway energy profile but not end state energy levels
State 1 and 2 are internal energy states, dq and
dw are energies exchanged with environment
Internal energy is measured against a reference,
not absolute level. Energy of interest in
biochemistry include:
- Translational, vibrational, rotational energy
- Chemical bonding; covalent and non-covalent
These energies can be converted and exchanged
with the surroundings as heat dq and/or work dw.