Question

work together to create a rule to help to determine if a change is considered to be a physical change or chemical change. use the rule to categorize the following: physical changes melting ice into water, tearing paper, rusting iron, cutting paper, baking a cake, crushing a soda can, boiling water chemical changes burning, vinegar reacting with baking soda making bubbles, milk souring, dissolving sugar in water

Explanation:

Rule:

• Physical Change: A change where the substance's chemical identity remains the same (no new substance formed). It involves changes in state (solid ↔ liquid ↔ gas), shape, size, or physical separation. Examples: phase changes (melting, boiling), cutting, tearing, crushing.
• Chemical Change: A change where a new substance is formed (involves chemical reactions, often with signs like color change, gas production, precipitate, heat/light, or odor change). Examples: rusting, burning, souring, reactions (vinegar + baking soda).

Categorization:

Physical Changes (no new substance):

• Melting ice into water (phase change, H₂O remains H₂O).
• Tearing paper (shape change, paper is still paper).
• Cutting paper (size/shape change, paper is still paper).
• Crushing a soda can (shape change, metal is still metal).
• Boiling water (phase change, H₂O remains H₂O).

Chemical Changes (new substance formed):

• Rusting iron (Fe → Fe₂O₃, new compound).
• Baking a cake (chemical reactions, new substances like CO₂, baked dough).
• Burning (combustion, new substances like CO₂, H₂O).
• Vinegar reacting with baking soda (CO₂ gas, new substances like NaC₂H₃O₂).
• Milk souring (lactic acid formed, new substance).
• Note: Dissolving sugar in water is physical (sugar dissolves, no new substance; it’s a mixture). If misclassified, correct it: dissolving sugar is physical.

Answer:

Rule:

• Physical Change: No new substance formed (changes in state, shape, size, or mixture without reaction).
• Chemical Change: New substance formed (via reactions, with signs like gas, precipitate, heat, odor, color change).

Categorized:

Physical Changes:

• Melting ice into water
• Tearing paper
• Cutting paper
• Crushing a soda can
• Boiling water
• Dissolving sugar in water (corrected, as it’s a physical mixture)

Chemical Changes:

• Rusting iron
• Baking a cake
• Burning
• Vinegar reacting with baking soda (making bubbles)
• Milk souring