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 non-equilibrium chemical thermodynamics. This appro
ach enables one to overcome some difficulties and ambiguities of the s
tandard thermodynamic description of complex chemical systems. In part
icular, the concept of thermodynamic coupling of chemical reactions ma
y be given a new qualitative and quantitative meaning.