Discussion

A sample of marble chips is weighed on an analytical balance before and then again after reacting with sulfurous acid. A noticeable loss of mass occurs, indicating that the marble, calcium carbonate, has reacted with the acid. It is changed to soluble calcium sulfite.

CaCO₃(s) + H₂SO₃(aq) → CO₂(g) + H₂O(l) + CaSO₃(aq)

Note also that the bromphenol blue indicator present in the sulfurous acid solution has changed color, providing a visual indication that some of the acid has reacted with the marble chips.

The mass before reacting with sulfurous acid was 109.14 g and the mass after reacting with sulfurous acid and drying was 108.89 g.