Physical and Chemical Changes

“The sum total of things was always such as it is now, and such it will ever remain," and that nothing is created from nothing, and nothing that disappears ceases to exist. - Epicurus (341-270 BC)

Matter Matter is everywhere. Matter is anything that takes up

space and has mass. Matter is constantly experiencing

both chemical and physical changes.

Physical Change Physical changes occur when

matter changes its properties but not its chemical nature.

The material still has the same chemical structure (generally these reactions can be considered

reversible)

Physical changes Could include:

Texture Shape Size Mass

Phase changes are physical changes

Physical Change

Chemical Change Chemical changes are changes that

matter undergoes when it becomes a new or different substance.

The material created has a different chemical structure

Chemical Change The indicators of a chemical reaction

include: Color change Production of a gas Production of light or heat A precipitate is formed

Example: lead nitrate and potassium iodide

Precipitate A precipitate is a solid that forms when

two liquids are combined.

Chemical Change A chemical change

occurs when fireworks are used. Fireworks are made of metals such as magnesium and copper. These change chemically as they light up the sky.

Is it a chemical or physical change?

Sugar dissolving in tea

•Chemical Change

•Physical Change

OOPS!Did it change size, color, shape (Physical

Change)?or

Did it become different matter (Chemical Change)?

Correct!

Is it a chemical or physical change?

Logs burning

•Chemical Change

•Physical Change

OOPS!Did it change size, color, shape (Physical

Change)?or

Did it become different matter (Chemical Change)?

Correct!

Is it a chemical or physical change?

Ice melting in a cup of water

•Chemical Change

•Physical Change

OOPS!Did it change size, color, shape (Physical

Change)?or

Did it become different matter (Chemical Change)?

Correct!

Is it a chemical or physical change?

Cutting paper

•Chemical Change

•Physical Change

OOPS!Did it change size, color, shape (Physical

Change)?or

Did it become different matter (Chemical Change)?

Correct!

Is it a chemical or physical change?

Crushing an aspirin

•Chemical Change

•Physical Change

OOPS!Did it change size, color, shape (Physical

Change)?or

Did it become different matter (Chemical Change)?

Correct!

Is it a chemical or physical change?

Metal rusting

•Chemical Change

•Physical Change

OOPS!Did it change size, color, shape (Physical

Change)?or

Did it become different matter (Chemical Change)?

Correct!

Is it a chemical or physical change?

Lighter fluid burning

•Chemical Change

•Physical Change

OOPS!Did it change size, color, shape (Physical

Change)?or

Did it become different matter (Chemical Change)?

Correct!

Is it a chemical or physical change?

An egg rotting

•Chemical Change

•Physical Change

OOPS!Did it change size, color, shape (Physical

Change)?or

Did it become different matter (Chemical Change)?

Correct!

Is it a chemical or physical change?

An egg breaking

•Chemical Change

•Physical Change

OOPS!Did it change size, color, shape (Physical

Change)?or

Did it become different matter (Chemical Change)?

Correct!

Law of Conservation of mass In a chemical reaction, matter is neither

created nor destroyed. The mass of a closed system will remain

constant Closed system - one that is isolated from the

surrounding environment, no matter can be exchanged

Open system - one in which matter and heat can be exchanged between the system and surrounding environment

Writing Activity Write a paragraph about the difference

between a chemical and physical change. Give examples of each.