Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The 1st Law of Thermodynamics in Chemical Reactions   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.

13
The categories of this paper are: quant-ph
18
The categories of this paper are: econ
16
The categories of this paper are: stat
6
The categories of this paper are: astro-ph
12
The categories of this paper are: nucl-th
2
The categories of this paper are: math
1
The categories of this paper are: cs
8
The categories of this paper are: hep-ex
26
The categories of this paper are: bayes-an
31
The categories of this paper are: ao-sci
34
The categories of this paper are: chem-ph
0
The categories of this paper are: hep-ph
7
The categories of this paper are: hep-th
30
The categories of this paper are: q-alg
29
The categories of this paper are: funct-an
9
The categories of this paper are: nlin