PHYSICAL & CHEMICAL CHANGES

REVIEW & REINFORCEMENT

How does one determine the difference between chemical and physical changes?

Matter can undergo 2 types of changes: physical changes and chemical changes.

Do you remember what the main differences are between physical and chemical changes?

Can you give any examples of a physical change or a chemical change?

It is important to note that all matter can go through changes!

PHYSICAL & CHEMICAL CHANGES

GOAL FOR TODAY:

While we have a pretty good understanding of the difference between physical and chemical changes, we have to learn a little bit more about how to determine the difference between these two types of changes to matter in everyday situations.

PHYSICAL & CHEMICAL CHANGES DEMONSTRATION Experiment #1: Vinegar and Sugar

Experiment #2: Vinegar and Baking Soda

So what clues can we use to determine if a chemical reaction has taken place? [Brainstorm & be ready to

share out!]

Physical changes

PHYSICAL CHANGES

Physical changes DO NOT change the structure of the matter when it is observed or described.

Structure refers to how the atoms are put together.

SOLUBILITY

Physical Changes: Solubility

Physical Changes

• Changes in the state of matter: only the state of the matter changes, the substance does not.

Miss Lamb,

Are you sure that when matter changes from one state to the next that it is only going through a physical change?

I mean, can you really prove it to me scientifically?

-Skeptical in Linglestown

Structure of water

Structure of ice

Structure of steam

Chemical Properties

CHEMICAL PROPERTIES

Chemical properties describe a change in structure.

The substance is forever changed, it can not be changed back.

CHEMICAL PROPERTIES:

During the demonstration of the baking soda and vinegar, we saw bubbles form, signaling a chemical reaction.

What other clues might signal a chemical reaction?

SIGNS OF CHEMICAL CHANGES

Clue Example

Changes in color [be careful here]

• green tomato turns red• cake browns in oven• apple in the air browns• fried egg

Changes in odor • burning wood• spoiled food

Changes in temperature without being heated/cooled

• rotting leaves in compost pile become warm

• hand warmer packs

Bubbles form • Baking soda & vinegar• Yeast & water

Gives off gas/gases • Burning wood gives off carbon dioxide and water vapor

• Yeast & water releases carbon dioxide gas

New solids form • Rust is created

LET’S CHECK & MAKE SURE WE UNDERSTAND!

“NAME THAT CHANGE!” CHALLENGE You will now be given the opportunity to travel around to different stations around the room.

Visit each station and follow the directions.

Determine whether the station represents a physical or a chemical change.

Justify and explain your answer.