Questions and Answers
Give an example of a physical change that can be reversed and one that cannot be reversed.
Reversible: Braiding your hair; Non-reversible: Cutting your hair.
List 3 examples of physical properties.
Malleability, hardness, and change in color.
How do you know if a chemical change has occurred?
A new substance is formed, a precipitate appears, or a gas is produced.
Give two examples of chemical properties.
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What kind of change occurs when a substance changes from one state to another state of matter?
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If atoms combine to form a compound, what type of change has occurred?
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A pat of butter melts and then burns in a hot frying pan. Which of these changes is physical and which is chemical?
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Define chemical change and physical change.
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Study Notes
Physical Changes
- Reversible Change: Example is braiding hair, which can be undone.
- Irreversible Change: Example is cutting hair, which cannot be restored.
Physical Properties
- Properties to consider include:
- Malleability: Ability of a material to be shaped or bent without breaking.
- Hardness: Resistance of a material to deformation or scratching.
- Change in Color: Observable alteration indicating a physical property may have changed.
Chemical Changes
- Indicators of a chemical change:
- Formation of a new substance.
- Production of a precipitate (solid that forms from a solution).
- Release of gas during the reaction.
Chemical Properties
- Key properties include:
- Reactivity: How a substance interacts with others, which can change its chemical structure.
- Flammability: The ability of a substance to ignite and burn in the presence of an ignition source.
State Changes
- A change from one state to another (solid, liquid, gas) is classified as a physical change.
Formation of Compounds
- Chemical Change: Occurs when atoms combine to create a new compound, changing the original substances at a molecular level.
Example of Dual Changes
- Melting and burning butter:
- Physical Change: Melting of butter as it retains its substance.
- Chemical Change: Burning of butter that produces new substances.
Definitions
- Physical Change: A change in which some properties may alter, but the substance remains unchanged.
- Chemical Change: A process where a substance undergoes a transformation, resulting in a new substance being formed.
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Test your understanding of physical changes and properties in Chapter 2 with these flashcards. Explore examples of reversible and irreversible changes, physical properties, and signs of chemical changes. Perfect for quick revision and self-assessment.
