In the given chemical reaction, calcium carbonate (CaCO3) is decomposing into carbon dioxide (CO2) and calcium oxide (CaO). The chemical equation can be summarized as follows:
\[ \text{CaCO}_3 \rightarrow \text{CO}_2 + \text{CaO} \]
According to the law of conservation of mass, the total mass of reactants must equal the total mass of products in a chemical reaction. Therefore, the total mass of the products will be the same as the mass of the reactant that is being decomposed.
In this case, the scientist is starting with 30 grams of calcium carbonate (CaCO3). Since there is no loss of mass due to the reaction itself (assuming it's a closed system), the total mass of the products (CO2 + CaO) will also be 30 grams.
Thus, the total mass of the products is 30 grams.