Common Reactions in Our Lives
Chemical reactions = when substances react
to form a new substance.
They happen all the time:
Antacid tablets
Banana ripening
Bleach
Baking Bread
Chlorine in pools
Digestion in our stomach
Identifying Gases
Oxygen
1. The glowing splint.
If the glowing splint ignites its oxygen
Hydrogen Gas
1. Add a match to the test tube and listen
for a pop or a squeal.
Carbon dioxide
Light a match watch the flame. If it
goes out its CO2
Chemical Reactions
Reactants
Before
Products
After
Evidence of Chemical Change:
Gases given off (bubbles)
Precipitate (solid) forming
Color change
Odor
Energy given off (temperature change)
2 types of special chemical reactions
1. Combustion
- a fuel burns in oxygen to produce
CO2 and H2O.
ex. Cellular respiration, burning a
candle.
C6H12O6 + O2
CO2 + H2O
Neutralization
When an acid neutralizes a base to become
more neutral. Tries to get to a ph of 7.
Antacids in your stomach. The products of
this are always some sort of salt and water.
Mg(OH)
2
+ HCl
MgCl + H O
2
2
Chemical reactions undergo energy
changes.
They can release a lot of energy into their
surroundings. So if a reaction creates a lot
of heat its Exothermic.
(cellular respiration, combustion)
If a reaction absorbs energy from its
surroundings, it feels cold. So a reaction
that cools down its surroundings is
Endothermic.
(photosynthesis, cold packs)