Physical vs. Chemical

What is a physical change?

• A physical change is a change that does not alter the chemical composition of a substance.
• A physical change involves a chemical reaction.
• A physical change alters the chemical composition of a substance.
• A physical change is a change that cannot be reversed.

What is a chemical change?

• A chemical change is a process where substances combine or break apart to form new substances.
• A chemical change is a physical alteration of a substance.
• A chemical change occurs when substances remain unchanged.
• A chemical change is a process that only involves temperature changes.

Physical or Chemical Change?

(a)  

Is cracking an egg physical or chemical change?

(a)  

Is baking the cupcakes physical or chemical change?

(a)  

What are some signs that a chemical change has occurred? 

• Melting of ice
• Dissolving sugar in water
• Mixing two liquids without any reaction
• Signs of a chemical change include gas production, color change, precipitate formation, temperature change, and light emission.

What happens during a state change of matter, like when water freezes?

• Water evaporates into steam when it loses heat.
• Ice melts into water when it gains heat.
• Water turns into vapor when it freezes.
• Water freezes into ice when it loses heat and its molecules arrange into a solid structure.