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Physical ChangeChemical before change is the same chemical
afterwards.
• Only its form has been altered.
• Examples:
• Big piece broken into smaller pieces
• Phase changes
• Shape change: bending a straw
Chemical ChangeChemical before change is not the same chemical after.Change in Properties:• Melting point, boiling points, density, color, taste, texture,
smell, etc. are now different.• Precipitation: solid forms when 2 liquids react when mixed• Gas production: Change in Energy:• Heat energy absorbed, heat energy released, light energy
released
Chemical or Physical Change?
Cutting paper?
PhysicalWhy?Paper beforePaper afterOnly altered its form.
Chemical or Physical Change?Ice melting?
PhysicalWhy?Water before, water after.
Just a phase change, solid -> liquid
Chemical or Physical Change?
Toast burning?ChemicalWhy?Change in properties.
Different smell, taste, color, texture.
Chemical or Physical Change?
Rocket fuel burning?
chemical
Why?Heat and light energy
released
Gas production
Chemical or Physical Change?
Metal rusting?chemicalWhy?Metal before, rust (iron
oxide) after
Color change (grey to red/orange),
strength change (strong to weak)
texture (smooth to powdery)
Chemical or Physical Change?Disappearing puddle?
Physical
Why?
Water before, water afterJust a phase change:
Liquid water to gaseous water
Chemical or Physical Change?Candle burning?ChemicalWhy?Change in energy: release of
light and heat energyWax reacts with oxygen in air and
produces carbon dioxide gas and water gas