Questions and Answers
Burning is always accompanied by the production of heat.
True
Photosynthesis is a physical change.
False
Digestion is a chemical change.
True
The change of colour in a slice of apple is a physical change.
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Rusting is a chemical change that affects copper articles.
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Oxygen plays a crucial role in rusting.
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Galvanisation prevents rusting by coating iron with copper.
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Rusting can be prevented by storing iron articles in airtight containers.
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The monetary loss due to rusting is very low.
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Neutralisation is a physical change.
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Study Notes
Rusting of Iron
- Rusting is a process that can be represented by the equation: Iron (Fe) + Oxygen (O2) + water (H2O) → rust (iron oxide Fe2O3)
- Rusting requires the presence of both oxygen and water (or water vapor)
- High moisture content in the air accelerates rusting
- Ways to prevent rusting:
- Applying a coat of paint or grease to prevent contact with oxygen and water
- Depositing a layer of metal like chromium or zinc on iron
Ozone Layer
- The ozone layer protects us from harmful ultraviolet radiation from the sun
- Ozone breaks down to form oxygen when absorbing ultraviolet radiation
- The breaking down of ozone is a chemical change
Chemical Changes
- Other examples of chemical changes:
- Magnesium ribbon burning in air to form magnesium oxide
- Food spoilage producing a foul smell
- Digestion
- Photosynthesis
- Neutralization of an acid with a base
- Chemical changes involve the formation of new substances
- Chemical equations use an arrow to imply "becomes" and do not need to be balanced at this stage
Physical and Chemical Changes
- Burning is accompanied by production of heat
- Fireworks explosion is a chemical change producing heat, light, sound, and unpleasant gases
- Chemical changes can result in significant effects, such as monetary loss due to rusting
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Description
Learn about the process of rusting, its chemical equation, and the required conditions for rusting to occur.
