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Is melting of a candle, a physical change or a chemical change or both. Explain why?
Burning of a candle is both physical and chemical change.
Physical changes:
While burning the candle the wax slowly melts as the candle gets smaller and this molten wax can be again solidified and will make it into a candle which means that it is a reversible change.
Chemical changes:
The heat produced by the candle consumes both the oxygen in the atmosphere, as well as the fuels coming from the flame. This will then lead to carbon dioxide emissions produced by the flame. This is an irreversible change.
Physical change is the change of that matter where only the appearance or molecular arrangement of matter changes without changing its composition.
Examples: Boiling and freezing of water, melting of wax, mixing sand and grains, crumpling a paper bag, chopping a wood etc.
Properties of physical change are as follows:
• Most of the physical changes are reversible. The original form of the matter can be attained.
• It is a temporary change and no new substance is formed.
• During a physical change, no energy is absorbed or released
• Physical change causes a change in physical properties such as shape, size, etc.
Chemical change: The change in which chemical properties of the matter change is known as chemical change.
During a chemical reaction, the chemical bonds between the molecules are broken and rearranged, and new bonds are formed resulting in the formation of new compounds.
Properties of chemical change are as follows:
1. Chemical changes are irreversible. The original form of the matter cannot be attained.
2. It is a permanent change and one or more new substance is formed.
3. During a chemical change, energy is produced in the form of heat, light or sound, while during a chemical reaction, energy is either absorbed or released.
4. Chemical change causes changes in the physical and chemical properties of the substance.
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