What is a physical change?

• A change that alters the form or appearance of matter without forming a new substance

• A change that forms a new substance with different properties

• A change that is always reversible

• A change that involves the formation of a gas

Explain how cutting an apple and letting it sit out for several hours demonstrates a chemical change.

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Applying

When sugar is added to tea, there is a physical change because the sugar and water mix but remain the same substances. If you evaporate the water out of the mixture, the sugar will remain at the bottom of the cup. This demonstrates that physical changes are often ___.

Which of the following is a sign of a chemical change?

• Change in color or odor

• Melting of ice

• Breaking a glass

• Mixing sand and water

Describe a real-world example of a chemical change you have observed and explain the evidence that indicates a chemical change occurred.

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Applying

A chemical change is a change in matter in which one or more new substances form. The new substances have different properties from the substances that existed before the change. For example, the elements hydrogen and oxygen react with each other to form the compound ___.

What distinguishes a chemical change from a physical change?

• Chemical changes form new substances with different properties, while physical changes do not.

• Physical changes are always irreversible, while chemical changes are reversible.

• Chemical changes involve the formation of a gas, while physical changes do not.

• Physical changes always involve a change in color or odor.