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Changes in Matter - What Kind of Change is It?

Magicians are not the only ones who can change one material into something completely different. Did you know that scientists, nature and even you can change one material into another?  We call this “magic” a chemical reaction.

In a chemical reaction matter is changed from one substance from one to another.

Burning wood changes the wood into ash. Water will react with iron to form a new product. Do you know what it is? If you have ever left your bicycle in the rain you probably know it is called rust.

Chemical reactions may also produce heat, light, bubbles or color changes. When the bike rusted, the metal turned a different color so we know that a chemical reaction occurred between the bike and the water. Please remember that not all color changes prove that a chemical reaction has taken place.

A physical change is different than a chemical change. Things that are changed physically do not turn into something else.

Breaking a match in two pieces is an example of a physical change. Lighting a match and letting is burn is an example of a chemical change.

Chemical reactions cause chemical changes. In a chemical reaction two or more substances, called the reactants, form different substances called products. In the above examples the wood and oxygen were the reactants that, when heated, formed the products of ash and smoke (gases). Water, iron and oxygen were the reactants that formed the product called rust.

Reactants
Products
Wood + oxygen (heat)
=
Ash + smoke
Water + iron + oxygen
=
Rust

What would happen if you were to change one of the reactants in a chemical reaction? What if, instead of water, you put grease or oil on your bike? Would you still get rust? Of course not. You would get a greasy bike!

Not all substances will react with each other. Grease + iron + oxygen will not cause a chemical reaction. Changing the reactants will change the results of the experiment.

Do it!

Examine the left side of the chart below. Decide if the action taking place is a physical change or a chemical reaction. Choose your answer in the column on the right. Then check your answers by highlighting the box below. Good luck!

Action taking place Type of Change

1. Glass breaking

2. Ice cube melting

3. Candle burning

4. Food digested in your stomach

5. Glass breaking

6. Marshmallow burning

7. Lake freezing

8. Bread baking

9. Sugar dissolving

10. Popsicle melting

11. Gasoline burned in an engine

12. Lake freezing

1. Physical change, 2. Physical change, 3. Chemical change, 4. Chemical change,5. Physical change, 6. Chemical change, 7. Physical change, 8. Chemical change, 9. Physical change, 10. Physical change, 11. Chemical change, 12. Physical change

utah state board of education This Sci-ber Text was developed by the Utah State Board of Education and Utah educators.