What is physical and chemical change?

Answer 1

Physical Change: A physical change is when the product's outer appearance has changed but it's still the product.

Chemical Change: A chemical change is when the product has changed completely to a new product.

Answer 2

Chemical changes are like when leaves change in the fall. That is an example of a chemical change. Physical changes are when water boils. The water turns into a vapor but it doesent change form in any way. All it does is change state. When the leaf changes in the fall, the chemicals inside of the leaf change colors and it goes on inside the leaf. That's the difference in physical and chemical changes.

Answer 3

1. A physical change can be undone, but a chemical change can not. For example, freezing water would be a physical change because it can be reversed, whereas burning wood is a chemical change, you can't 'unburn' it

2. A physical change is a change where no new substance is created; a chemical change results in creating 1 or 2 new substances. Again, consider the previous examples: Freezing water into ice just results in water molecules stuck together tighter - it's still H2O. Whereas burning wood results in ash, carbon dioxide, etc, all new substances which weren't there when you started.

Answer 4

Chemical Changes

Chemical changes take place on the molecular level. A chemical change produces a new substance. Examples of chemical changes include combustion (burning), cooking an egg, rusting of an iron pan, and mixing hydrochloric acid and sodium hydroxide to make salt and water.

Physical Changes

Physical changes are concerned with energy and states of matter. A physical change does not produce a new substance. Changes in state or phase (melting, freezing, vaporization, condensation, sublimation) are physical changes. Examples of physical changes include crushing a can, melting an ice cube, and breaking a bottle.

How to Tell Chemical & Physical Changes Apart

A chemical change makes a substance that wasn't there before. There may be clues that a chemical reaction took place, such as light, heat, color change, gas production, odor, or sound. The starting and ending materials of a physical change are the same, even though they may look different.

Answer 5

The physical change doesn't modify the chemical composition of the molecule.
The chemical change modify the chemical structure of the molecule and a new compound is formed.