Question

What happens to mass during chemical and physical changes?

Answer 1

Not a lot......................

Explanation:

In every chemical and (non-nuclear) physical process EVER observed, mass is CONSERVED. That is, if you start with `10*g` of reactant, from all sources, AT MOST you can get `10*g` of product. In practice you are not even going to get that, because losses always occur on handling, and every step in a synthesis will remove a proportion of product.

Organic chemists, who regularly perform multi-step natural product syntheses, are well aware of these problems. They might start out with kilos of starting material, but in a multistep synthesis, it would not take too many steps, even with +80% yields, before they are dealing with milligram quantities.