Transcript snc2l u2l3 physical and chemical changes

Physical and Chemical
Changes
Lesson 3
February 3rd, 2011
Physical Change

In a physical change, the substance involved
remains the same (chemically). The
substance may change form or state,
however. All changes of state are physical
changes.
Physical Change
Examples: Dissolving a substance in a
liquid, breaking something.
 NOTE: Most physical changes can be
reversed

Observing Chemical
Properties (3)

A chemical property describes the ability of
a substance to change into a new substance
or substances.

In order to view a chemical property a
chemical change must occur.
Chemical change - the formation of a new
substance or substances with new properties.
 A chemical reaction is a process in which a
chemical change occurs.


Chemical properties include how a
substance interacts with other substances
Chemical Properties
1. Combustibility is the ability of a substance
to burn. In order to burn a substance
requires Oxygen
Chemical Properties

Light sensitivity is a chemical property of
that can cause new substances to form
when light hits it.
Chemical Properties
3. Reacting with an acid is a chemical
property where when acid is poured on a
substance it produces a gas and bubbles.
Clues that a chemical
change has occurred
Evidence of
Chemical Change
Example
Change in Colour Metal is silvercoloured; rusted metal
is brown
Picture
Clues that a chemical
change has occurred
Evidence of
Chemical Change
Example
Bubbles
Sodium
appear or a
bicarbonate
gas is formed creates a gas
when dropped in
water.
Picture
Clues that a chemical
change has occurred
Evidence of
Chemical Change
Heat or light is
produced or
absorbed
Example
A burning candle
gives off light and
heat
Picture
Clues that a chemical
change has occurred
Evidence of
Chemical Change
A solid is
formed
Example
Precipitate
Picture
Clues that a chemical
change has occurred
Evidence of
Chemical Change
The change
cannot be
reversed
Example
A fried egg
cannot be
converted back to
a raw egg.
Picture

WHMIS, HHPS, and MSDS labels provide
information about what might happen when
chemical changes occur. This information is
intended to protect you.

Physical and Chemical Changes Worksheet
Complete
 If time permits we will start the lab.
