ok so im learning about physical and chemical change and im just lost. like for instance, if u are cooking an egg would it be physical cuz it changs from a liquid to a solid?

No, it is a chemical change. The egg changes color, and the protein in the egg is denatured (protein bonds are broken). In most foods, heat causes protein bonds to break (meat gets tender, for instance).

on physical bonds, usually they are reversible. No way to unharden a boiled egg...

ok that makes sense. so then would boiling water be chemical too? or since it changes fro water to evaporation would it be physical?

water boiling is a physical change. It can recondense to water from the steam.

ok so then like ice would be physical cuz u can freeze and unfreeze as much as u would like. and the boiling water would be physical cuz evaporation changes back into water. is that right?

yes, ice melting is a physical change.

so then gasoline would be chem cuz it cant change back. but then what about polution?

thank u sooo much!

I understand your confusion! Let's break it down.

When it comes to physical and chemical changes, we need to understand the key differences between them. A physical change involves a change in the state or appearance of a substance without a change in its chemical composition. On the other hand, a chemical change involves a new substance being formed with completely different chemical properties.

When you cook an egg, the change from a liquid (raw egg) to a solid (cooked egg) is indeed a physical change. The egg undergoes a change in its physical state from a liquid to a solid due to the application of heat. However, the chemical composition of the egg remains the same. The proteins in the egg denature and coagulate, leading to the formation of a solid mass.

To determine whether a change is physical or chemical, you can consider the following steps:
1. Observe the change: Notice any physical or visual differences before and after the change.
2. Analyze the composition: Determine whether there is a new substance formed with different chemical properties.
3. Assess the reversibility: Check if the change is easily reversible or irreversible.

In the case of cooking an egg, since the change is only a state change and the original substance can be restored by heating further, it supports the explanation that it is a physical change.

Remember that understanding the concept is more important than memorizing specific examples. Applying the definitions and steps mentioned above should help you determine whether a change is physical or chemical.