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A class observes two demonstrations: water changing into steam and a plece of wood burning and producing smoke. A student concludes that both demonstrations must be examples of a chemical change because a gas is produced in each. Is the student's condusion accurate? Explain your answer, referring to both demonstrations.

3 answers

The student's conclusion that both demonstrations represent chemical changes is partially accurate, but it requires clarification. Let's analyze each demonstration.

  1. Water Changing into Steam:

    • This process involves the physical change of water (liquid) into steam (gas). When water is heated, its molecules gain energy and move faster, leading to a phase transition from liquid to gas. This change does not alter the chemical structure of the water molecules (H₂O); they remain the same before and after the change. Therefore, the production of steam from water is a physical change, not a chemical change.

  2. Wood Burning and Producing Smoke:

    • This process is a chemical change. Burning wood involves combustion, a reaction between the wood (primarily composed of cellulose) and oxygen from the air, resulting in the production of new substances, such as carbon dioxide, water vapor, ash, and smoke. The molecular structure of the original substances is altered during this process, indicating a chemical change.

In summary, while the student is correct that gas is produced in both demonstrations, it is important to distinguish between the types of changes. The transformation of water to steam is a physical change, while the burning of wood is a chemical change. Thus, not all scenarios that produce gas are examples of chemical changes.

One paragraph please

The student's conclusion that both demonstrations represent chemical changes is only partially accurate. In the case of water changing into steam, this process is a physical change, as the water molecules remain chemically the same (H₂O) when they transition from liquid to gas due to heating. In contrast, the burning of wood is a chemical change because it involves a combustion reaction that alters the molecular structure of the wood, producing new substances such as carbon dioxide, water vapor, ash, and smoke. Therefore, although gas is produced in both cases, it is crucial to recognize that only the burning of wood exemplifies a chemical change, while the conversion of water to steam is a physical change.