Which experiment did Antoine Lavoisier perform to help demonstrate the Law of Conservation of Mass?

• A. He burned wood in an open flame and measured the mass of the ashes.
• B. He mixed vinegar and baking soda in an open beaker and observed the bubbles.
• C. He heated mercury in a closed container to form mercury(II) oxide and measured the mass before and after the reaction.
• D. He dissolved sodium chloride in water and observed the change in taste.

Answer: (C)

Verified step by step guidance

1. Understand the Law of Conservation of Mass, which states that mass is neither created nor destroyed in a chemical reaction; the total mass of reactants equals the total mass of products.
2. Identify that to demonstrate this law experimentally, one must measure the mass of substances before and after a chemical reaction, ideally in a closed system to prevent loss of matter.
3. Recognize that Antoine Lavoisier's key experiment involved heating mercury in a closed container to form mercury(II) oxide, allowing precise measurement of mass before and after the reaction without any loss of material.
4. Note that by comparing the mass of mercury and oxygen before the reaction and the mass of mercury(II) oxide after the reaction, Lavoisier showed that the total mass remained constant, supporting the Law of Conservation of Mass.
5. Conclude that experiments involving open systems or observations without mass measurements (like burning wood in open air or mixing vinegar and baking soda in an open beaker) do not effectively demonstrate this law due to possible loss of gases or other materials.