Video narration
Why are melting ice and cooking an egg different kinds of change? In the kitchen, both look different, so it's tempting to treat them alike. Yet ice, as it melts, changes from solid to liquid and is still water. Nothing new has formed. That's a physical change: its form or state changes, but no new substance appears. Melting is often easy to reverse by cooling, but reversibility alone doesn't define the category. Now think of an egg cooking. With the egg, heat changes more than its state or shape. It changes as it heats, and new substances form. That's a chemical change: a change that forms new substances. The important question isn't just whether it looks different. Has a new substance formed? So, melting ice is physical: it's still water. Cooking an egg is chemical: new substances form.