Question

part 1: analyze the scenario
for each situation below:

• decide whether it is a physical change or chemical change
• explain why using evidence from your notes (phase change, chemical formula, signs of a chemical change, etc.)

1. a puddle of rainwater slowly disappears on a warm sidewalk.

type of change: _______________
explanation:
_________________________
_________________________

1. a bicycle left outside develops rust after several weeks.

type of change: _______________
explanation:
_________________________
_________________________

1. sugar is stirred into hot tea until it is no longer visible.

type of change: _______________
explanation:

Explanation:

1.

A puddle disappearing is a physical change (evaporation). The water changes from liquid to gas (water vapor) without altering its chemical formula ($H_2O$ remains $H_2O$), just its phase.

The rainwater (liquid $H_2O$) undergoes evaporation (a phase change) to become water vapor (gas). No new substance is formed, so it is a physical change.

2.

Rusting a bicycle involves iron reacting with oxygen and water to form iron oxide (rust, a new substance with a different chemical formula). This is a chemical change due to the formation of a new compound.

Answer:

Type of change: Physical change