States of Matter and Changes

The distinction between physical and chemical change is whether the

Composition of matter changes

Burning a piece of paper — physical or chemical change? Why?

Chemical change because a new substance was created from a reaction with oxygen.

How can you make sure dissolving sugar in water is a physical change?

When you evaporate the water, the sugar crystals come back

When liquid nitrogen rapidly evaporates at room temperature, causing frost to form on nearby surfaces, is this a physical or chemical change? Why?

Physical change because the chemical only changes it state — liquid to gas.

Broiling a steak — physical or chemical change? Why?

Chemical Change because when you apply heat it causes the proteins to change their structure

Cutting a piece of paper — physical or chemical change? Why?

Physical change because you are cutting a piece of paper into smaller pieces

Physical Change

Particles before and after remain the same, which means composition did NOT change.

Chemical Change

Particles before and after are different, which means composition DID change.

State of Matter

The physical forms in which a substance can exist: solid, liquid, gas.

Examples of physical changes

Melting, freezing, boiling, dissolving, cutting, crushing.

Examples of chemical changes

Burning, rusting, cooking, fermentation, tarnishing.

Indicator of chemical changes

Color change, gas production (bubbles/fizz), temperature change without heating/cooling, formation of a precipitate (solid), odor change.