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2-1 What is Energy
CHEMICAL ENERGY
The energy that matter possesses because of
its chemical makeup
Comps. have chem. energy bec. of the
atoms they contain and the bonds that hold
them together
CHEMICAL BOND – a mutual attraction
betw. diff. atoms that binds the atoms together
KINETIC ENERGY
Energy a moving object has bec. of its
motion
Atoms & molecs. are in constant motion
POTENTIAL ENERGY
energy an object has bec. of its position
position of atoms
• When positions change, bonds are formed or broken
& energy is absorbed or released
 rxns. change positions of atoms and potential energy
changes
All chemical & physical changes
involve a change in energy.
freezing
evaporating
dissolving
explosion
burning
ENERGY
the capacity to do work
LAW OF CONSERVATION
OF ENERGY
in any chemical or physical process, energy
is neither created nor destroyed
total amt. of energy in the universe is constant
energy just changes form
Energy can be transferred.
HEAT
the sum total of kinetic energy of the
particles in a sample of matter
can be transferred due to a difference in temp.
SYSTEM
a specific portion of matter in a given
region of space that has been selected for
study during an experiment or observation.
complex or simple
everything outside system is surroundings
Heat transfer:
System to surrounding
Surroundings to system
TEMPERATURE
a measure of the average kinetic energy of
the particles in a sample of matter.
heat flows from high temp. to low temp.
Thermometer measures temp.
matter expands as its temp. incr
Celsius scale.
0oC is freezing pt. of water
Kelvin scale
0K is absolute zero – lowest temp. theoretically
possible
oC
= K – 273
K = oC + 273
Diff. substs. incr. temp. diff. amt.
with same amt of heat added
SPECIFIC HEAT CAPACITY (cp) – The
amt. of heat energy required to raise the
temp. of 1 gram of a subst. by 1K (or 1 Co)
expressed in J / g . K (or J / g . Co)
Joule (J) – SI unit of energy
Heat energy (q) = m c t
Matter and energy are closely
related
Einstien – E = mc2
implies matter and energy are equivalent
can be changed into ea. other