Question

1. give five examples of chemical transformations (changes) that you make use of in your daily activities. indicate what the “chemical” is in each of your examples, and how you recognize that a chemical change has taken place.

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5.

Explanation:

1. Burning of Wood (Campfire): When wood burns, it reacts with oxygen to form carbon dioxide, water vapor, and ash. New substances (like CO₂, ash) are formed, indicating a chemical change.
2. Rusting of Iron (Bicycle Chain): Iron in the chain reacts with oxygen and moisture in the air to form iron oxide (rust). Rust is a new substance, so this is a chemical change.
3. Cooking an Egg: The proteins in the egg undergo denaturation (a chemical change) when heated. The egg white and yolk change from liquid to solid, and new chemical structures form.
4. Fermentation (Making Yogurt): Bacteria convert lactose (sugar in milk) into lactic acid. This changes the milk's texture and taste, and lactic acid is a new substance, so it's a chemical change.
5. Digestion of Food (Stomach): Enzymes in the stomach break down food (e.g., proteins into amino acids) into smaller, absorbable molecules. New substances are formed, so it's a chemical change.

Answer:

1. Burning of Wood (Campfire) - New substances (CO₂, ash) formed.
2. Rusting of Iron (Bicycle Chain) - Iron oxide (rust) formed.
3. Cooking an Egg - Protein denaturation, new structures.
4. Fermentation (Making Yogurt) - Lactic acid formed from lactose.
5. Digestion of Food (Stomach) - Food broken into new molecules.