How are chemical reactions involved in the transformation of matter?
That is basically what chemical reactions are -- the transformation of matter. I'll explain a bit below.
Every so often, I get interested in nuclear stuff. Power plants, disaster, atom bombs...stuff like that.
When Fukushima had its "meltdown" after the earthquake (meltdown is in parentheses because in one case, it was the spent fuel pool that was the problem, not necessarily the reactor, but in another case, it was a reactor), there was a big blast that blew the top off the reactor building of two or three buildings. Those explosions are a good demonstration of "chemical reactions involved in transformation of matter".
When the fuel (or spent fuel) got hot because the pumps weren't circulating water, the zircaloy casing (good for neutrons) started to decompose. This stuff is reactive, and so it reacted fiercely with the water, pulling the hydrogens off to make
This Hydrogen gas accumulated in the upper parts of the building and eventually exploded. The explosion turns the Hydrogen gas back into water.
It is sort of like a stability rollercoaster. You take fairly stable, unreactive water, and add enough energy to it (and a reactive substance like zircaloy decomposition) and you chemically change one matter (water) into a different matter (Hydrogen gas...and Oxygen). That Hydrogen gas is suddenly much more unstable and higher energy. With an ignition source, that hydrogen slides down the thermodynamic hill to reform stable water, and in the process sheds a bunch of the energy it had gained (in the form of blowing the roof off the top of the building).
Big oversimplification, but my brain works like a Far Side comic strip sometimes.