A Koenig Born diagram is a diagram used to remember the Maxwell's relations
In the figure
below , U stands for Internal Energy
, H for Enthalpy
, G for Gibb's free energy
, and A for the Helmholtz free energy
, V is Volume
, P is pressure
, T is temperature
and S is entropy
These are arranged in a Koenig Born diagram as follows:
V A T
S H P
In addition there is an arrow from S to T and from P to V.
The diagram is read as follows. For example the top row of the square would be read as dA is a function of dV and dT and dA=-PdV-SdT.
The coefficient of dV is -P because the arrow links V to P and the connection goes against the arrow.Similarly the coefficent of dT is S because the arrow links T to S and the the minus sign is because the connection goes against the arrow.