Cooking and Food:
* Baking bread: Yeast ferments sugars in the dough, producing carbon dioxide gas, which makes the bread rise. This is a chemical reaction that changes the dough's composition.
* Cooking an egg: The heat causes the proteins in the egg to denature and solidify, changing its texture and color.
* Burning wood: Wood reacts with oxygen in the air, producing heat, light, ash, and gases (like carbon dioxide). This is a combustion reaction.
* Fruit ripening: Chemical reactions within the fruit change its color, taste, and texture.
* Spoiling food: Bacteria and fungi break down food molecules, leading to changes in smell, taste, and appearance.
Cleaning and Personal Care:
* Washing dishes: Dish soap breaks down grease and oils into smaller molecules that can be easily washed away.
* Using bleach: Bleach reacts with stains, breaking them down and making them less visible.
* Hair dyeing: The chemicals in hair dye break down the pigment in hair and deposit new color.
* Toothpaste: Toothpaste contains chemicals that help to remove plaque and whiten teeth.
Other Examples:
* Rusting of iron: Iron reacts with oxygen and water to form rust (iron oxide). This is a chemical reaction that weakens the iron.
* Burning fuel: Gas, oil, and wood are burned in engines and furnaces, releasing energy through combustion reactions.
* Photosynthesis: Plants use sunlight, water, and carbon dioxide to create glucose (sugar) and oxygen. This is a vital chemical reaction for life.
* Fireworks: The chemical reactions in fireworks produce light, heat, and noise.
* Batteries: Chemical reactions in batteries convert chemical energy into electrical energy.
Key things to remember about chemical changes:
* New substances are formed: The original substances are transformed into something new with different properties.
* Often irreversible: It's hard to reverse the change (though some are reversible under specific conditions).
* Energy changes: Chemical changes often involve the release or absorption of energy (heat, light, etc.).
