Chemical and Physical Changes

Chemical and Physical Changes

SC.5.P.9.1 - I can compare and contrast physical changes and chemical changes.

Chemical and Physical Changes

• Matter can undergo two types of changes: physical changes and chemical changes.

• A chemical change involves a change in the identity or chemical composition of a substance, such as:

  • Burning, rusting, and rotting.

• A physical change involves changes to the form of a substance, but not to its chemical identity, such as:

  • Freezing, melting, evaporating, and dissolving.

Multiple Choice

Which type of change involves a change in the identity or chemical composition of a substance?

• Physical change

• Chemical change

• Freezing

• Melting

Chemical Change

Chemical change involves a change in the identity or chemical composition of a substance. It results in the formation of new substances with different properties. Examples include burning, rusting, and digestion.

Multiple Choice

Which of the following is an example of a chemical change?

• Cutting paper

• Folding paper

• Burning paper

• Washing paper

Burning Paper

Burning paper is an example of a chemical change. When paper burns, it undergoes a chemical reaction called combustion, where it combines with oxygen to produce heat, light, and new substances like ash and smoke. This process is irreversible and releases energy.

Multiple Choice

Which of the following describes a chemical change to a slice of bread that is the result of heat?

• The bread is cut.

• The bread is frozen.

• The bread is dropped.

• The bread is toasted.

Signs of a Chemical Change

• Gas Production: Bubbles form when a gas is produced in a reaction involving a liquid.

• Temperature Change: Chemical changes can give off or absorb heat.

• Precipitate Formation: A solid substance separates from a solution, such as a solid sinking to the bottom of a liquid.

• Color Change: A change in color can indicate a chemical reaction.

Multiple Select

Which of the following is an indicator of a chemical reaction?

• Gas Production

• Temperature Change

• Precipitate Formation

• Color Change

• Size Change

Taking Away or Adding Heat...

If you TAKE AWAY heat, an object gets colder... a gas will condensate into a liquid, a liquid will freeze into a solid.
If you ADD heat, an object gets warmer... a solid will melt into a liquid, a liquid will evaporate into a gas.

Solid melts into a Liquid

Liquid evaporates into Gas

Adding Heat to a Substance

Gas condensates into Liquid

Liquid freezes into Solid

Removing Heat from a Substance

Multiple Choice

Dominic leaves a glass of water outside overnight. The next morning, the liquid has changed into a solid. Which of the following most likely caused this to occur?

• Addition of heat

• Addition of a gas

• Removal of heat

• Removal of a gas