SNC1D – Chemistry Unit
Date: ___________________________
Physical and Chemical Change Worksheet
Complete the worksheet using the textbook page references: pp. 181, 182, 184
PHYSICAL CHANGES (Read pp. 181-182)
In a physical change, the composition of the substance remains exactly the SAME.
No NEW substances are made.
Example: Changes of State
An ice cube left out on a table melts. The ice cube was a cold SOLID, and now it has
changed into a cold LIQUID. Was a new substance produced? NO
In this example, the particles that make up WATER did not change. Only the
ARRANGEMENT of the water particles changed.
Therefore, a change of state is a PHYSICAL change.
Example: Dissolving of Substances
If you add a teaspoon of sugar to a large pot of hot water and stir, the sugar seems to have
DISAPPEARED into the water. This may lead you to think that its composition has changed.
All the particles of sugar are CLOSER together in the solid state. When they are dissolved,
the sugar particles become SEPARATED spread out among the WATER particles, and are
no longer VISIBLE in solution. If you taste the water, you can tell that the SUGAR is still
there because the solution tastes SWEET. If you allow all the water to EVAPOURATE the
sugar reappears at the bottom of the pot.
Therefore, dissolving is a PHYSICAL change.
CHEMICAL Changes (Read pp. 184)
A chemical change is always accompanied by a change in the STARTING substance(s) and
the production of one or more NEW substances. The original substances do not
DISAPPEAR. Instead, the components of the original substances are RE-ARRANGED in the
process of forming a new substance.
Clues of Chemical Changes:
When determining whether a chemical change has occurred, one can look for evidence such
as:
ü A Change of COLOUR - a new substance has formed that has a different COLOUR
than the original substance. (Not a blending of the colours)
ü A change of ODOUR - a new substance has formed that has a detectable ODOUR
ü BUBBLES are visible that are not caused by heating – a new substance is produced in
the form of a GAS.
ü A new SOLID is seen – a new substance that is produced does not dissolve in the
mixture and shows up as a SOLID; the SOLIDS that are formed in this way are often
powdery and are called PRECIPITATE.
ü A change in TEMERATURE or LIGHT - energy is released or absorbed during the
chemical change, and is detected as a change in TEMERATURE or light.
Practice:
Description
Physical
or
Chemical
Change
A sheet of paper is crumpled into
a ball.
P
A sheet of paper is set on fire and
burns to ashes.
C
Steel wool is left outside over the
winter. The steel wool rusts.
C
A teaspoon of white sugar
(sucrose) dissolves in a glass of
warm water.
P
Vinegar is poured over a teaspoon
of baking soda. The white
powdered baking soda fizzes, and
bubbles form.
C
Reasoning
(describe why it is a physical or chemical
change)
SNC1D–ChemistryUnit Date:_____________________________________
Assessment:PhysicalandChemicalChange
Statewhethereachofthefollowingchangesare(P)physicalor(C)chemical.Thefirstoneisdoneasanexample.
#
Situation
PorC?
BriefExplanation(Clue)
1
icemelts
P
A change of state has occurred.
2
gasolineexplodes
C
3
sulfurisburned
C
4
waxhardensonacandle
P
5
ironrusts
C
6
paperisshredded
P
7
silvertarnishes C
8
carbondioxidefizzesoutofpop
C
9
amatchisstruck
C
10
alcoholburns C
11
muddywaterisallowedtosettle
P
12
woodischopped
P
13
aneggisfried C
14
vinegarisaddedtobakingsoda
C
15
formationofclouds
P
16
breadgrowingmouldy C
17
sandingapieceofwood
P
18
sodiumhydroxidedissolvesinwater
P
19
magnesiumisburnedtoproducemagnesiumoxide
C
20
waterisheatedandchangedtowatervapour
P
21
souringofmilk(yuck!)
C
22
tireisinflatedwithair P
23
waterisabsorbedbyapapertowel
P
24
sugardissolvesintea
P
25
Challengingsituations:
grassgrowinginalawn C
26
foodisdigestedinthestomach
C