7 Difference Between Physical and Chemical Changes Class 7

Understanding the differences between physical and chemical changes is essential in science, as it helps us to know how substances interact and transform. A physical change occurs when the form or appearance of a substance changes, but its chemical structure remains the same. Examples include changes in state, like ice melting into water, or breaking a glass. In contrast, a chemical change happens when a substance transforms into a completely new substance with different chemical properties, such as when iron rusts or wood burns. Here are 7 differences between physical and chemical changes:
1. In a physical change, the substance’s appearance or form changes, but its chemical composition remains the same, while in a chemical change, the substance’s chemical structure changes, forming a new substance.
2. Physical changes are generally reversible, such as freezing and melting water, whereas chemical changes are often irreversible, like burning paper.
3. During a physical change, no new substances are formed, but a chemical change results in the creation of one or more new substances.
4. Physical changes usually do not involve energy changes, except for changes in state, whereas chemical changes often involve energy changes like heat release or absorption.
5. In physical changes, the mass of the substance remains constant throughout the process, while in chemical changes, the mass of the original substances may change due to the formation of new substances.
6. Physical changes are typically easy to observe, such as cutting or bending materials, whereas chemical changes can be harder to detect and may require indicators like color change or gas production.
7. Physical changes do not alter the molecular structure of a substance, but chemical changes involve a reorganization of atoms, leading to a change in the molecular structure.

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