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Chemistry Review
Balancing Equations
In a chemical equation each side must have the same
number and type of atoms.
Examples:
H2 +
Na +
O 2  H2O
H2  NaH
NEVER CHANGE THE CORRECT FORMULA IN ORDER TO
BALANCE AN EQUATION! COEFFICIENTS ONLY!
Challenge
__C5H12 + __O2 __H2O + __CO2 + Energy
_____ C _____
_____ H _____
_____ O _____
Law of Conservation of
Matter
The law states that matter cannot be created or
destroyed.
In a chemical equation, each side of the equation
must consist of the same number of molecules.
C(s) + O2(g)  CO2(g)
This chemical equation is balanced
since there is one carbon atom and
two oxygen atoms on each side,
thus proving the Law of
Conservation of Matter.
Renewable vs. Nonrenewable
Renewable energy sources are resources that can be
sustained
Examples: Solar Energy, Wind Energy, Geothermal
Energy, and Hydropower
Non-renewable energy sources are resources that
cannot be sustained
Examples: Gasoline, Coal, Natural Gas, and Diesel
Physical and Chemical Changes
Physical properties are observed with our senses and
can be determined with out destroying the object
Example: Color, shape, mass, length and odor
Chemical properties indicate how a substance reacts
with something else.
Example: Iron rusting, wood burning and copper
oxidizing
Physical and Chemical Changes
Physical Change: Identity stays the same
Chemical Change: Identity changes
Examples
Sodium hydroxide dissolves in water ____________
Evaporation ___________
Milk sours ___________
Wood rotting __________
A tire is inflated with air __________
More Examples…
Evaporation: _________
Melting: ___________
Wood- rotting: _________
Freezing: ___________
Metals, Non Metals, Metalloids
(semi-metals)
Properties of Each
 Metals:
•
•
•
•
Conduct
Malleable
Reacts with acid
Shiny
 Non-Metals:
•
•
•
•
Do not conduct
Brittle
Do not react with acids
Dull/not shiny
 Metalloids:
• Conduct
•Malleable
•Do not react with acids
•Dull/not shiny
Conservation of Energy
Exothermic Reaction- A reaction in which energy is
given off or released and bonds form. As a result,
new compounds are formed
Endothermic Reaction- A reaction that requires the
addition of energy. As a result, bonds break.
Chemical
potential
4H + 2O
energy
II
2 H2 + O2
2 H2O
III
I
Time
If the overall chemical potential energy decreases then the reaction
is exothermic.
If the overall chemical potential energy increases then the reaction
is endothermic.
Therefore this is an _________________ reaction.
Types of Energy
Kinetic Energy- The energy an object possesses due
to its motion.
Potential Energy- Stored energy.
There are many different forms of energy such as:
Heat
Light
Chemical
Sound
Energy Examples
A rolling ball _______________
A photovoltaic cell ______________
A rollercoaster at its peak _____________
Steve jogging ______________
A parked car _______________
Heat of Combustion
Heat of Combustion: The quantity of thermal energy
given off when a certain amount of a substance
burns.
Heat of Combustion: Thermal energy released
Mass of substance burned
Thermal energy= M × C × ΔT
Thermal energy= Mass of water × Specific heat of
water × Change in temperature of water
Example
How much energy (kilojoules) is released by
completely burning 25.0 mol hexane, C6H14?
Solution:
25.0 mol hexane ×
4141 kJ
1 mol hexane
= 104,000 kJ
- Burning 25 mol hexane would thus release
104,000 kJ of Thermal Energy
Specific Heat of Water
4.2 J/g0C
1 Cal/ goC
Specific Heat Capacity: quantity of thermal energy
needed to raise the temperature of 1 gram of a
material by 1oC.
The End (: