Question

1. identify each change below as physical or chemical. then list the evidence for that change.

change	chemical or physical?	evidence
mixing sugar and water	▼	▼
mixing baking soda and vinegar	▼	▼
a piece of metal is bent in half	▼	▼
crushing an aspirin into a powder	▼	▼
baking cookies	▼	▼
methanol is burned	▼	▼
glass breaking	▼	▼

Explanation:

Step1: Analyze "Cutting your hair"

A physical change doesn't form new substances. Cutting hair only changes its shape/length, no new substance. So it's physical. Evidence: No new substance, just size/shape change.

Step2: Analyze "Mixing sugar and water"

Sugar dissolves, but it's still sugar (no new substance). Physical change. Evidence: Dissolution, no chemical reaction (sugar can be recovered by evaporation).

Step3: Analyze "Mixing baking soda and vinegar"

Baking soda (sodium bicarbonate) and vinegar (acetic acid) react to form CO₂, water, and sodium acetate. New substances, so chemical. Evidence: Gas production (bubbling), temperature change, new substance.

Step4: Analyze "A piece of metal is bent in half"

Bending metal changes shape, no new substance. Physical. Evidence: Shape change, metal remains metal.

Step5: Analyze "Crushing an aspirin into a powder"

Only changes size (from tablet to powder), no new substance. Physical. Evidence: Size reduction, same substance.

Step6: Analyze "Baking cookies"

Ingredients (flour, sugar, etc.) react with heat to form new substances (like caramelization, protein denaturation). Chemical. Evidence: Color change, smell change, new texture (baked vs. raw), gas production (leavening).

Step7: Analyze "Methanol is burned"

Methanol (CH₃OH) burns to form CO₂ and H₂O. New substances, chemical. Evidence: Combustion (flame, heat), gas production, new substances.

Step8: Analyze "Glass breaking"

Breaks into pieces, no new substance. Physical. Evidence: Shape/size change, glass remains glass.

Answer:

Change	Chemical or Physical?	Evidence
Mixing sugar and water	Physical	Sugar dissolves, no new substance (sugar can be recovered)
Mixing baking soda and vinegar	Chemical	Gas (CO₂) production, temperature change, new substances formed
A piece of metal is bent in half	Physical	Shape change, metal is still the same substance
Crushing an aspirin into a powder	Physical	Size change, aspirin remains aspirin
Baking cookies	Chemical	Color change, smell change, new substances (baked structure) formed
Methanol is burned	Chemical	Combustion (flame, heat), CO₂ and H₂O produced
Glass breaking	Physical	Shape/size change, glass is still glass