HOW CAN MATTER
CHANGE?
Physical Vs Chemical Reaction
CHEMICAL CHANGE
• Occurs when there is a change in the arrangement of
atoms
• Caused by breaking and reforming of bonds.
• A new substance is produced:
• Multiple substances combine to form a new substance
• An old substance breaks apart to form new substances
EVIDENCE OF CHEMICAL CHANGES – GAS RELEASED
• Baking Soda & Vinegar
• CO2 is produced is evidence of a chemical change
• Typically bubbles form during this time from gas
formation
• Adding Zinc to HCl causes bubbles to form
• Hydrogen gas being released
EVIDENCE OF CHEMICAL CHANGES – SALT
FORMATION
• Salt is Formed when there is a
reaction with an acid and metal
• Produce a hydrogen gas and a salt (forms
as a crystal)
• Acids and Bases react together to
form a neutralization reaction
• Acid + Base -> Water + Salt
EVIDENCE OF A CHEMICAL REACTION – TARNISH
• Metals exposed to oxygen tarnish, which is
a chemical change
• Tarnish is the actual substance that is made.
EVIDENCE OF A CHEMICAL REACTION – SOLID FORMS
FROM LIQUIDS
• A new solid chemical is formed from the
reaction
• Typically falls out of a solution to bottom of
test tube
• Solution often turns cloudy until material
settles to the bottom of the solution
• Silver nitrate is added to sodium chloride and a
white powder is formed
EVIDENCE OF A CHEMICAL REACTION – CHANGE IN
TEMPERATURE
• The reaction causes a increase or decrease in temperature
• Endothermic – Heat being absorbed form the air and stored in
bonds
• Air around the reaction and container the reaction is in gets cooler
• Exothermic – Heat being released into the air from breaking
bonds
• Air around a reaction and the container the reaction is in gets warmer
EVIDENCE OF A CHEMICAL REACTION – ODOR FROM
REACTION
• An odor being released is evidence of a chemical change.
• Ammonia carbonate is heated and the odor of ammonia is
given off
PHYSICAL CHANGE
• Change in appearance without changing the identity of
the substance.
• New Substance is not produced
• Change in size (breaking or adding pieces)
• Expand or contract due to temperature changes
• Phase change
WHAT IS IT?
• Water Melting
• Marshmallow Toasting
• Marshmallow on Fire
• Popcorn Popping
• Silver Plate Turning Black
• Car Fender Rusting
• Wood Burning
• Taking a Bite of an Apple
• Chewing an Apple