Question

describing the amount of product in a chemical equation marcia is given an incomplete chemical equation that includes the number of nitrogen atoms present in the products of the reaction. how can she conclude that the reaction started with three nitrogen atoms?

Explanation:

To determine if the reaction started with three nitrogen atoms, Marcia can use the law of conservation of mass (or law of conservation of atoms). This law states that in a chemical reaction, the total number of atoms of each element in the reactants must equal the total number of atoms of that element in the products. So, if the products have three nitrogen atoms, the reactants must also have three nitrogen atoms (since atoms are neither created nor destroyed in a chemical reaction, only rearranged).

Answer:

Marcia can use the law of conservation of mass (conservation of atoms). This law states that the number of atoms of each element in reactants equals that in products. Since the products have three nitrogen atoms, the reactants (start of reaction) must also have three nitrogen atoms (as atoms are conserved, not created/destroyed, just rearranged in reactions).