Question

which procedure could be used to demonstrate that matter is conserved during a chemical change or reaction? (1 point)
find the mass of a piece of paper. tear the paper into smaller pieces. find the mass of the pieces.
find the mass of a stick of butter. heat the butter until it melts. find the mass of the melted butter.
find the mass of a log. burn the log until it turns to ash and smoke. find the mass of the ash.
find the mass of an acid and a base. combine them to produce water and a salt. find the mass of the water and salt.

Explanation:

• Tearing paper is a physical change, not a chemical change.
• Melting butter is a physical change (change of state), not a chemical change.
• Burning a log: When a log burns, it reacts with oxygen in the air. Measuring only the mass of the ash does not account for the gases (like carbon - dioxide, water vapor) that are produced as part of the chemical reaction.
• Combining an acid and a base is a chemical reaction (neutralization reaction). According to the law of conservation of matter, the mass of the reactants (acid + base) should be equal to the mass of the products (water + salt) if the system is closed (to account for any gases, but in a simple sense of mass before and after reaction for demonstration purposes).

Answer:

Find the mass of an acid and a base. Combine them to produce water and a salt. Find the mass of the water and salt.