How did Lavoisier demonstrate that matter is neither created nor destroyed during a chemical reaction?

• A. He carefully measured the mass of reactants and products in a sealed container and found they were equal.
• B. He used a microscope to watch atoms disappear and reappear during reactions.
• C. He observed that gases released during reactions always increased the total mass.
• D. He showed that burning substances in open air always resulted in a loss of mass.

Answer: (A)

Verified step by step guidance

1. Understand the Law of Conservation of Mass, which states that matter cannot be created or destroyed in a chemical reaction.
2. Recognize that Lavoisier designed experiments to test this law by carefully measuring the mass of substances before and after a chemical reaction.
3. Note that he used a sealed container to ensure no matter could enter or leave the system during the reaction, preventing loss or gain of mass from the surroundings.
4. Measure the mass of the reactants inside the sealed container before the reaction begins.
5. After the reaction, measure the mass of the products inside the same sealed container and compare it to the initial mass to confirm they are equal, demonstrating that matter is conserved.