Tearing of paper is a physical change but burning it is a chemical change. Explain.
The correct answer and explanation is:
Tearing paper is considered a physical change, while burning paper is a chemical change. The distinction between physical and chemical changes lies in whether the substance undergoes a transformation in its chemical structure.
When paper is torn, it is simply being divided into smaller pieces. The substance itself remains the same, with no change in its molecular composition. In this process, the paper retains its properties, such as its texture, color, and chemical structure. Tearing does not produce any new substances, meaning no new chemical bonds are formed or broken. Therefore, tearing is classified as a physical change.
On the other hand, when paper is burned, it undergoes a chemical reaction. Burning paper involves a process known as combustion, where the cellulose in the paper reacts with oxygen in the air. This reaction results in the formation of new substances, such as carbon dioxide, water vapor, and ash. The bonds between atoms in the paper molecules are broken, and new bonds are formed as a result of the chemical reaction. This is an irreversible process, meaning the original paper can no longer be recovered. Because burning paper results in the formation of new chemical substances, it is considered a chemical change.
In summary, the key difference between tearing and burning paper is the change in the molecular structure. Tearing paper only alters its physical form without changing its chemical identity, while burning paper causes a chemical transformation that creates entirely new substances.