Physical & Chemical Changes
Physical Change | Chemical Change | |
Definition |
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Properties |
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Examples |
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Chemical Properties:
Properties of a substance observed when and how it interacts with other substances
Examples of Chemical Properties
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iron rusts in moist air (with the oxygen in the air), but gold does not
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hydrogen burns in oxygen, but nitrogen does not (they are both gases that make-up air)
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zinc reacts with acid, but glass does not
Activity: Give three reasons why fireworks are examples of chemical changes
A. Physical Properties:
Properties that can be observed without changing the substance into another substance
Intrinsic Physical Properties: Properties that do no change with amount of substance
- State at room temperature
- Density
- Colour
- Luster
- Electrical Conductivity
- Melting Point
- Odour
- Boiling Point
- Solubility in water
- Attraction to/by magnets
- Mass
- Shape
- Texture
Illustrate how a substance reacts or fails to react with other substances to produce new substances
Example: Sodium fizzes vigorously in water, silver tarnishes and dynamite explodes.
1. Flammability (does it burn easy?) | |
2. Ease of oxidations (does it rust or corrode rapidly?) | |
3. Reaction with acid or base | |
4. Heat of combustion | |
5. Does the substance support combustion | |
6. Does the substance decompose on heating |
C. Physical Reaction:
1. Alters only the form or state of a substance | |
2. Does not change the chemical composition |
- ice at room temperature
- rock crushing
- liquid water
- clouds