Question

Based on the results of this lab, write a short paragraph that summarizes how to distinguish physical changes from chemical changes.

Answer 1

Physical changes alter a substance’s form or physical state but not its chemical identity — examples include melting, freezing, dissolving, tearing, or grinding; these changes are often reversible and the original substance’s composition remains the same. Chemical changes produce one or more new substances and are indicated by signs such as a persistent color change, gas evolution (bubbling/fizzing), formation of a precipitate, or a temperature/light change (release or absorption of energy); they are often not easily reversible. In the lab, classify a change as chemical if you observe new substances or energetic effects; if only shape, phase, or mixing without new properties occurs, classify it as physical.