  In the previous papers of the author it has been shown that the 1st law of
thermodynamics in chemical reactions is the following one: dU=dQ+PdV+SUM In the
present paper this theory was developed and it has been shown that the 1st law
of thermodynamics in chemical reactions has the following form: dC=-dU+dA and
-dU=dQ where dC is the change in the chemical energy, dU is the change in the
internal energy. Internal energy is the energy of thermal motion of molecules.
