Why does the law of conservation of mass require that chemical equations be balanced?

• A. Because balancing equations ensures that all reactants are completely consumed.
• B. Because it prevents the formation of any side products.
• C. Because the total mass of reactants must equal the total mass of products in a chemical reaction.
• D. Because it allows chemists to predict the color changes during a reaction.

Answer: (C)

Verified step by step guidance

1. Understand the law of conservation of mass: it states that mass cannot be created or destroyed in a chemical reaction.
2. Recognize that in a chemical reaction, atoms are rearranged but the total number of each type of atom remains the same before and after the reaction.
3. Realize that balancing a chemical equation ensures the same number of atoms of each element appear on both sides of the equation, reflecting the conservation of mass.
4. Note that if the equation is not balanced, it would imply that atoms are lost or gained, which contradicts the law of conservation of mass.
5. Therefore, balancing chemical equations is necessary to accurately represent the mass and atoms involved, confirming that the total mass of reactants equals the total mass of products.