The fundamental differential equations of chemical thermodynamics with
in the De Donder (stoichiometric) approach are reformulated in terms o
f a special class of chemical reactions, which we call response reacti
ons, RERs. The RERs have the remarkable property of being independent
of the actual choice of the stoichiometrically independent reactions,
by means of which the chemical processes in the system considered are
usually described. The concept of RERs is shown to be applicable in bo
th equilibrium and nonequilibrium chemical thermodynamics. This approa
ch enables one to overcome some difficulties and ambiguities of the st
andard thermodynamic description of complex chemical systems. In parti
cular, the concept of thermodynamic coupling of chemical reactions may
be given a new qualitative and quantitative meaning.