The burning of a tree to form ashes is considered a chemical change because it involves the transformation of the substance's chemical composition and the formation of new substances. Here's a breakdown of why it is classified as such:
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Chemical Reaction: When a tree burns, it undergoes combustion, a chemical reaction between the tree's organic materials (mainly cellulose, lignin, and water) and oxygen from the air. This reaction produces various gases (like carbon dioxide and water vapor) and new solid materials (like ash).
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Formation of New Substances: The materials that make up the tree (wood) are chemically altered during the burning process. The original chemical compounds in the wood are broken down and reorganized into new compounds, notably carbon dioxide and the ash that remains post-combustion.
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Irreversibility: Chemical changes are typically irreversible or very hard to reverse. Once wood has burned and converted into ash and gases, the original wood cannot be restored. This contrasts with physical changes, like melting or freezing, which can be reversed.
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Energy Change: Burning a tree also releases energy in the form of heat and light, a characteristic of many chemical reactions.
Overall, since the burning process changes the chemical identity of the materials involved and results in the creation of new substances, it is classified as a chemical change.
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