Transcript Chapter 2 Energy & Matter

Chapter 2 Energy &
Matter
Energy – the capacity to do
work or produce heat
–
Examples of energy: moving car,
sunlight, food, oil
3 categories of energy:
1. Radiant – all forms of light
2. Kinetic energy – movement energy
3. Potential energy – stored energy
Gravitational energy – energy of position
Electrical energy
Chemical energy
Measuring energy
1 calorie (cal) – amount of heat
to raise 1 gram of water 1 Co
1 food calorie (Cal) = 1000 cal =
1 kcal
Chocolate bar is about 200 Cal
(200 kcal)
SI unit of heat is the joule (J)
1 cal = 4.184 J
Law of Conservation of
energy
Energy cannot be created or
destroyed but can be changed
from one form to another.
Energy is
not lost
Energy transformation
Kinetic
Food
chemical
potential
Gravitati
onal
potential
Heat and
sound as arrow
strikes the
ground
but
changes
forms.
Kinetic
Temperature (3 temp. scales)
Fahrenheit, Celsius, Kelvin
Develop equations to convert F
to C and C to F
T
180 Fo = 100 Co
9 Fo
C + 32 oF
F=
5 Co
5 Co
(F – 32 Fo)
C=
9 Fo
Kelvin temp scale – there are
no negative temperatures
– The coldest temperature is 0 K
which is -273 oC
oK = oC + 273
(see page 64 “Pursuing Absolute Zero”)
If matter reached absolute zero, all
motion would stop
The closer any thing gets to
absolute zero the harder it is to
remove any more heat.
It is a natural limit in nature (like the
speed of light)
Matter
Anything that has mass and occupies
volume
States of Matter
• Solid – holds a particular
shape and has definite
volume
• Liquid – no particular shape
but has definite volume
• Gas – no definite shape or
volume, fills all available
space
• Plasma – like gas only exists
at high temps (millions of
degrees)
On the sun and in a lightning bolt
H
E
A
T
I
N
G
Changes in state – by heating and cooling
Properties of matter – anything that can be
used to describe matter
1. Physical properties – properties that can
be determined without a chemical
reaction
2. Chemical properties – properties that
can only be determined by a chemical
reaction
Physical change – no new substance
produced
Chemical change – new substance
produced (something that was not there before)
Law of Conservation of Matter – matter
cannot be created or destroyed
Antwan Lavoisier (luhv-wahz-ee-ay) – father of
modern chemistry, careful experiments and
precise measurements
Elements and Compounds
• Element – a
substance that cannot
be separated into
simpler substances by
a chemical change
- Is listed on the
Periodic Chart
• Compound – two or
more elements
combined
Na
H 2O
Sc
Element Compound Element
SC
Compound
O2
Element
O3
Element
Mixture – two or more
substances stirred
together but not
chemically combined
– Heterogeneous
mixture – contains
visibly different parts
(even very small
particles)
– Homogeneous mixture
– the same throughout
Separating Mixtures
– Can be separated by
physical means;
filtration,
crystallization,
distillation,
chromatography