this is the first time I have heard of chemical and kinetic reactions having anything to do with conversion of energy to mass and vice-versa.
Note to creationists: The above is called learning (also humility, a character feature of Christ that creationists don't display very often)
Note also that 99% of the websites discussing combustion and nuclear energy will not say that either. If fact, probably 90% of them will say that combustion conserves mass unlike nuclear energy which converts mass to energy.
But once again, think of what we have. We have mathematical models of "fictitious" particles, atoms, molecules and how they are held together.
In combustion, we are changing the "binding energy" of the atoms in the molecules resulting in an energy release.
In fission, we are changing the "binding energy" of the nuclei of the atoms resluting in an energy release.
In fusion, we are changing the "binding energy" of the nuclei of the atoms resulting in an energy release.
That "binding energy" is what holds the particles together. We talk of Nuclear energy, we talk of chemical energy. Only because the chemists have beat it into our heads, do we find it hard to say that combustion converts mass to energy.
(Examples above all considered to be exothermic reactions)