Physical and Chemical Changes

Front

What is a physical change?

Back

A physical change is a change that affects one or more physical properties of a substance without altering its chemical composition. Examples include melting, freezing, and dissolving.

Front

What is a chemical change?

Back

A chemical change is a change that results in the formation of new chemical substances. It involves a chemical reaction and can be identified by changes such as color change, temperature change, gas production, or the formation of a precipitate.

Front

What evidence indicates a chemical change has occurred?

Back

Evidence of a chemical change includes unexpected color changes, temperature changes, gas production (bubbles), and the formation of a precipitate.

Front

What happens to iron when it rusts?

Back

When iron rusts, it undergoes a chemical change where it reacts with oxygen and moisture in the air to form iron oxide, a new substance.

Front

What is a precipitate?

Back

A precipitate is a solid that forms and settles out of a liquid mixture during a chemical reaction.

Front

Can a physical change produce a new substance?

Back

No, a physical change does not produce a new substance; it only changes the form or appearance of the substance.

Front

What is an example of a chemical change?

Back

Burning wood is an example of a chemical change, as it produces ash and smoke, which are new substances.

Front

What is an example of a physical change?

Back

Dissolving salt in water is an example of a physical change, as the salt can be recovered by evaporating the water.

Front

What is the difference between a physical change and a chemical change?

Back

A physical change alters the form or appearance of a substance without changing its chemical composition, while a chemical change results in the formation of new substances.

Front

What does it mean when a substance undergoes a color change?

Back

A color change can indicate a chemical change has occurred, especially if it is unexpected and not due to mixing or dilution.