Lesson 3 Physical and Chemical Changes
What is the law of conservation of mass?
matter cannot be created or destroyed
physical change
A change in a substance that does not change its identity
chemical change
A change in matter that produces one or more new substances
How is baking a cake a chemical change?
Change in Color, production of an odor
How do higher temperatures influence a chemical change?
Chemical reactions often happen more easily.
Give three examples of a physical change.
Cutting your hair, melting butter, bending a paper clip
A chemical change occurs when one or more substances stay the same but have different properties.
False
Matter is lost when a candle is burned.
False
The formation of a precipitate signals a physical change.
False
How are physical and chemical changes different?
Physical change affects one or more physical properties. Chemical changes occur when a substance changes into new substances.
A physical change is a change that affects one or more physical properties of a substance.
True
The chemical change results in the formation of new substances.
True
When an ice cube melts, it is still water.
True
When your body digests food, the food is changed into new substances.
True
