Physical and Chemical Changes
Physical changes involve changes in size, shape, or state of a substance without changing its chemical makeup. Chemical changes occur when two or more substances interact with each other to form a new substance. Examples of physical changes include melting, freezing, and evaporating; examples of chemical changes include burning, fermentation, and rusting.
Physical and Chemical changes
Physical changes are changes that alter a substance's physical properties, such as its size or shape, but do not change its chemical composition. Examples of physical changes include crushing, cutting, melting, freezing, boiling, and dissolving.
Chemical changes are changes that alter a substance's chemical composition and produce one or more new substances. Examples of chemical changes include burning, rusting, and fermentation.
A reversible change is a physical or chemical change that can be undone by a second change. For example, melting ice can be reversed by freezing the liquid water back into a solid.
Did you know?
Physical changes often involve a change in size, shape, or state of matter, but not in chemical composition. For example, when water melts, it turns from a solid to a liquid. Chemical changes involve a change in the chemical composition of a substance, which is why they are also called chemical reactions. For example, when baking soda and vinegar are mixed, a chemical reaction happens. Chemical changes are usually irreversible, meaning they cannot be undone. Physical changes, on the other hand, are usually reversible, meaning they can be undone.
What are some examples of physical changes that you can observe in your everyday life?
How do chemical changes differ from physical changes?
How do scientists use physical and chemical changes to their advantage?
What have you learned from studying physical and chemical changes?
Brain break: Draw a giant cupcake with wings and a superhero cape floating in the sky
In pairs: Select one task
Question: What are the differences between physical and chemical changes?
Physical changes involve changing the form or appearance of a substance, but not its chemical composition. Chemical changes involve a chemical reaction and the formation of new substances. Physical changes can usually be reversed, but chemical changes usually cannot.
A: Draw a picture to illustrate a physical change and a chemical change. B: Pretend you are a scientist and explain the differences to a colleague.
Burning paper is an example of a _______ change.
Which of the following is a physical change?
- Melting ice
- Baking a cake
- Rusting iron
'Rusting of iron' is an example of what type of change?
Boiling water to form steam is an example of what type of change?
Which statement describes a chemical change?
- An apple being cut in half
- Wood burning into ashes
- A candle melting
Work together in pairs: What are three examples of physical changes and three examples of chemical changes?