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.