Which of the following is not a physical change?
In the realm of chemistry and physics, understanding the difference between physical and chemical changes is crucial. While physical changes involve alterations in the form or appearance of a substance without changing its chemical composition, chemical changes result in the formation of new substances with different properties. This article aims to explore various examples and determine which of the following scenarios represents a physical change rather than a chemical one.
Physical Change vs. Chemical Change
To clarify the distinction between physical and chemical changes, let’s consider some examples:
1. Melting ice: When ice melts, it changes from a solid to a liquid state. However, the chemical composition of water remains the same, making it a physical change.
2. Boiling water: Similar to melting ice, boiling water involves a phase change from liquid to gas. Again, the chemical composition of water remains unchanged, making it a physical change.
3. Dissolving sugar in water: When sugar dissolves in water, it forms a homogeneous mixture. Although the sugar molecules are no longer visible, the chemical composition of both sugar and water remains the same, classifying this as a physical change.
4. Rusting iron: Rusting is a chemical change. When iron reacts with oxygen and moisture, iron oxide (rust) is formed, which has a different chemical composition than iron.
5. Burning wood: Burning wood is a chemical change. The combustion process transforms the wood into carbon dioxide, water vapor, and ash, which have different chemical compositions from the original wood.
Determining the Physical Change
Now that we have discussed various examples, let’s identify which of the following scenarios is not a physical change:
A. Melting ice
B. Boiling water
C. Dissolving sugar in water
D. Rusting iron
E. Burning wood
The correct answer is:
D. Rusting iron
Rusting iron is a chemical change because it involves the formation of a new substance (rust) with a different chemical composition than iron. The other examples (melting ice, boiling water, and dissolving sugar in water) are physical changes as they do not alter the chemical composition of the substances involved.
