[thackney]

Are you claiming the 4 hydrogen atoms and 2 oxygen atoms on the left side of the equation have a different mass than right?

E = M x C² is only applicable when converting mass to energy. A chemical reaction does not do this. It changes chemical energy as found in the molecular bonds and results in a change in heat.

[ColdWater]

Time for your education update:

http://www.phys.unsw.edu.au/einsteinlight/jw/module5_equations.htm

[djf]

Suppose we have a molecule of sodium chloride floating in space.

We can bombard it with a photon that has exactly the amount of energy needed to break the bond between the sodium atom and the chlorine atom.

So now we have an atom of sodium floating around, an atom of chlorine floating around, and no photon.

The photon is gone. It had mass and energy. It’s energy is represented by E=hf, where f is the frequency, and h is Plancks constant. It’s mass is then hf/C squared.

That mass went somewhere. It is now shared between the sodium and chlorine atoms.