Which statement best explains how the movement of energy can be tracked in a chemical system?

• A. By observing the changes energy causes to matter, such as temperature or phase changes.
• B. By counting the number of atoms present in the system.
• C. By measuring the mass of the system before and after a reaction.
• D. By determining the color of the substances involved.

Answer: (A)

Verified step by step guidance

1. Understand that energy itself cannot be directly observed, but its effects on matter can be measured.
2. Recognize that energy changes in a chemical system often cause observable changes such as temperature variations or phase transitions (e.g., solid to liquid).
3. Know that counting atoms or measuring mass does not directly track energy movement, as these relate to matter quantity, not energy flow.
4. Realize that color changes may indicate chemical changes but do not directly quantify energy transfer.
5. Conclude that the best way to track energy movement is by observing the changes energy causes to matter, such as temperature or phase changes.