Use the chemical reaction to answer the question.

In a chemical reaction, the law of conservation of mass states that matter cannot be created or destroyed. Therefore, the total mass of the reactants must equal the total mass of the products.

In this reaction, 30 grams of calcium carbonate (CaCO3) is heated to form carbon dioxide (CO2) and calcium oxide (CaO). Since the total mass of the reactants (30 grams) is equal to the total mass of the products, the total mass of the products will also be 30 grams.

So, the answer is:

30 grams