Sally carries out the following chemical reaction in an open container. MnO2 (s) + 4HCl (aq) MnCl2 (aq) + 2H2O (l) + Cl2 (g)

She finds that the total measured mass of the products is less than the mass of the reactants. How can she best explain this difference in mass between the products and reactants?

1Mass was not actually conserved in this reaction

2Because the products are all liquid or gas, they cannot be measured accurately

3The water formed in the reaction made up the mass of the chlorine gas that was released

4Some of the mass in the product was converted into gas, which was released into the air