Combustion is a chemical change. It involves the rapid oxidation of a substance, typically accompanied by the release of heat and light, resulting in the formation of new chemical compounds and altering the chemical composition of the original substance. 1
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Key Takeaways: Is Combustion a Physical or Chemical Change?
- Combustion is a chemical change because it involves a chemical reaction and the formation of new chemical compounds.
- During combustion, the original substances (fuel and oxygen) are transformed into new compounds through the rearrangement of atoms and the breaking and forming of chemical bonds.
- Combustion is not a physical change because it alters the chemical composition of the substances involved, unlike physical changes that only affect the physical properties of a material.
Why is combustion a chemical change?
Combustion is considered a chemical change because it involves a chemical reaction. Chemical changes involve the rearrangement of atoms and the formation of new chemical substances with different properties. In the case of combustion, a substance reacts with oxygen to produce heat, light, and new chemical compounds. 2
During combustion, a fuel (such as a hydrocarbon like methane or gasoline) combines with oxygen in the presence of a flame or spark. 3
The reactants undergo a chemical reaction, breaking and forming bonds to produce new compounds. For example, in the combustion of methane (CH4), it reacts with oxygen (O2) to produce carbon dioxide (CO2) and water (H2O).
The combustion process releases energy in the form of heat and light. 4 This energy is the result of the rearrangement of atoms and the breaking and forming of chemical bonds.
The new compounds formed during combustion have different properties than the original fuel, such as different chemical compositions and physical states.
Additionally, combustion is often accompanied by noticeable changes, such as the production of flames, smoke, or ash. These observable changes further demonstrate that a chemical reaction is taking place.
In summary, combustion is considered a chemical change because it involves a chemical reaction where the original substances (fuel and oxygen) are transformed into new compounds with different properties (such as carbon dioxide and water) through the rearrangement of atoms and the breaking and forming of chemical bonds.
Why is combustion not a physical change?
Combustion is not considered a physical change because it involves a change in the chemical composition of the substances involved. In a physical change, the identity and composition of the material remain the same, and only its physical properties, such as shape, size, or state, may be altered. 5
During combustion, the reactants (fuel and oxygen) undergo a chemical reaction, resulting in the formation of new chemical compounds. The bonds between atoms are broken and reformed, leading to the creation of entirely different substances.
For example, when a hydrocarbon fuel undergoes combustion, it produces carbon dioxide and water. The original fuel is transformed into new compounds with distinct chemical properties.
Furthermore, combustion is typically accompanied by the release of energy in the form of heat and light. This energy is a result of the chemical reactions occurring within the system.
Physical changes, on the other hand, do not involve the release or absorption of energy due to the rearrangement of atoms and the formation of new chemical bonds.
In summary, combustion is classified as a chemical change rather than a physical change because it involves a transformation of the substances at the molecular level, leading to the creation of new chemical compounds and the release of energy.
Further reading
Is Condensation a Physical or Chemical Change?
Is Sugar Dissolving in Water a Physical or Chemical Change?
Is Salt Dissolving in Water a Physical or Chemical Change?
Is Burning of a Candle a Physical or Chemical Change?
Is Burning of Paper a Physical or Chemical Change?
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References
- The Chemistry of Combustion. (n.d.). The Chemistry of Combustion. https://www.chem.fsu.edu/chemlab/chm1020c/Lecture%207/01.php
- Combustion | Definition, Reaction, Analysis, & Facts. (n.d.). Encyclopedia Britannica. https://www.britannica.com/science/combustion
- Hydrocarbon combustion – Energy Education. (n.d.). Hydrocarbon Combustion – Energy Education. https://energyeducation.ca/encyclopedia/Hydrocarbon_combustion
- Combustion – Wikipedia. (2016, July 1). Combustion – Wikipedia. https://en.wikipedia.org/wiki/Combustion
- Changes in Matter: Physical vs. Chemical Changes. (n.d.). Changes in Matter: Physical Vs. Chemical Changes. https://education.nationalgeographic.org/resource/changes-matter-physical-vs-chemical-changes