Question

Which observation provides the best evidence that a chemical change formed a new substance in the beaker?

1) The temperature of the beaker did not have any noticeable changes
2) The mass of the substances in the beaker increased
3) A red precipitate formed where the substance was poured into the beaker
4) The precipitate separated from the solution and fell to the bottom of the beaker

Answer 1

The observation that provides the best evidence of a chemical change in the beaker is the formation of a red precipitate.

Step-by-step explanation:

Observations that help to indicate a chemical change include:

• Temperature changes (either the temperature increases or decreases).
• Light given off.
• Unexpected color changes (a substance with a different color is made, rather than just mixing the original colors together).
• Bubbles are formed (but the substance is not boiling-you made a substance that is a gas at the temperature of the beginning materials, instead of a liquid).

Based on the provided options, the observation that provides the best evidence that a chemical change formed a new substance in the beaker is option 3: A red precipitate formed where the substance was poured into the beaker. The formation of a precipitate is an indication of a chemical change, as a new substance is formed when two or more solutions react.