Review: Physical and Chemical Changes

Review: Physical and Chemical Changes

Physical Change

  • A change (of state or form) in which a ______is not

formed and you can get the original substance ______.

  • Change involving:

Melting, ______, ______,

______, ______

Chemical Change

  • A change in which a ______is formed and you cannot get the original substances back easily.
  • How to recognize a chemical change:
  • A new ______is produced
  • A new odour and/or ______is produced
  • ______or ______is produced
  • Bubles of ______are formed
  • A ______(insoluble solid) is formed

Using the information above, complete the following table:

Change / P / C / Why?
A pie is baked
Chocolate melts
A match is lit
Wood is rubbed with sandpaper
An iron bar is heated until its red hot
A banana turns brown
A day old fish begins to smell
A balloon bursts
Your hair is cut
Ashes form when wood is burned
Change / P / C / Why?
Broken glass is crushed
Wire rusts
A firecracker goes BANG
A silver spoon tarnishes
Sugar is dissolved in coffee
Milk turns sour

Place a check in the appropriate column:

Change / Physical
Change / Chemical
Change
Salt dissolves in water.
Hydrochloric acid reacts with magnesium to produce hydrogen gas.
A piece of copper is cut in half
A sugar cube is ground up.
Water is heated and changed to steam.
Iron rusts.
Ethyl alcohol evaporates.
Ice melts.
Milk sours (goes bad).
Sugar dissolves in water.
Sodium and potassium react violently with water.
Pancakes cook on a griddle.
Grass grows on a lawn.
A tire is inflated with air.
Food is digested in the stomach.
Water is absorbed by a paper towel.
Ethyl alcohol boils at 79°C.
Paper burns.
Water freezes at 0°C.
Change / Physical
Change / Chemical
Change
Fireworks explode.
Alka-Seltzer gives off carbon dioxide when added to water.
Clouds form in the sky.

Now your knowledge of the two types of changes will be put to the test! Classify the changes listed below as either physical or chemical, and then give a reason for your decision. The first one has been done for you!

Change / Type / Reason
A newspaper yellowed after a few weeks / Chemical / Colour change is permanent
The steel wool turned the black pot a shiny silvery colour
Acid caused limestone to fizz
The back steps are rotting out
Spilled gasoline dried but left a bad odour in the room
The gravy in the refrigerator jelled
Red meat turned brown as it cooked
You got a cavity in your tooth
The paint on your car turned dull
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