Transcript Matter * States of Matter, Properties and Changes

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Matter takes up space and has mass
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Matter is made of atoms, usually chemically
bonded into molecules
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Exists in different states
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There are 4 states of matter: solid, liquid, gas,
and plasma
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State of a sample of matter depends on the
kinetic energy of the molecules or atoms in
the sample
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Kinetic energy is the energy of moving things
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Kinetic energy is the energy of moving things
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Kinetic energy moves from areas of higher
energy to areas of lower energy
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High energy
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Kinetic energy is measured in Joules (J)
low energy
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Solids have a definite shape and a definite
volume
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The atoms and molecules that make a solid,
vibrate in place but do not move around
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Particles in solid matter are held close
together by forces between them
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Particles vibrate but don’t have enough
energy to move out of position
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Liquids have a fixed volume, but take the
shape of the container in which they are
found
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The atoms and molecules that make a liquid
can flow around each other
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Particles in liquid matter are held close
together by forces between them
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Particles are close enough so that liquid
matter has a definite volume
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Particles have enough energy to move over
and around each other
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Gases have neither a definite shape nor
volume
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They take the shape of their container
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Particles of a gas have enough energy to
separate completely from one another
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Particles of a gas are not close together so
they can be squeezed into a smaller space
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Particles have enough energy to move in all
directions until they have spread evenly
throughout their container
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Plasma is a gaslike mixture of positively and
negatively charged particles
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They have so much energy that they collide
violently and break apart into charged
particles
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Found in lightning bolts, neon signs, Northern
lights, and stars
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It is made of electrons and positive ions that
have been knocked apart by collisions at
very high temperatures or in situations where
the matter has absorbed energy
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Least common state of matter on Earth but
is the most common state of matter in the
universe, because stars are made of matter in
the plasma state
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Almost all matter expands when it gets
hotter and contracts when it cools
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When matter is heated the particles move
faster, vibrate against each other with more
force
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Particles spread apart slightly in all directions
and the matter expands
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This effect happens in solids, liquids, and gases
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Examples are the liquid in a thermometer
and expansion joints in roads and buildings
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When matter gains or loses energy, it can
change from one state to another
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Different states of matter correspond to
different amounts of energy, these amounts
are specific to particular kinds of matter
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Temperature can be used to measure the
amounts of energy present in the matter
Boiling: liquid changes to a gas
 Freezing: liquid changes to a solid
 Condensing: gas changes to a liquid
 Melting: solid changes to a liquid
 Evaporating: liquid changes to a gas (but a
temperatures lower than the boiling point)
 Subliming: solid changes into a gas without
becoming liquid (opposite of sublimation is
deposition)
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Boiling point: temperature at which a liquid
becomes a gas, this temperature is an
identifiable characteristic for different
substances
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Melting point: temperature at which a solid
becomes a liquid
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Substances condense or boil at their boiling
point, depending on whether energy is being
added or taken away
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Substances melt or freeze at their melting
point, depending on whether energy is being
added or taken away
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Transitions between solid, liquid, and gaseous
phases typically involve large amounts of
energy compared to the energy needed to
change the temperature of a solid or liquid
or gas.
It takes lots of energy to change states
(temperature stays constant until state is
completely changed).
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If heat were added at a constant rate to a
mass of ice to take it through its phase
changes from solid to liquid water and then
to steam, the energies required to accomplish
the phase changes would lead to plateaus in
the temperature vs time graph.
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http://group.chem.iastate.edu/Greenbowe/sec
tions/projectfolder/flashfiles/propOfSoln/collig
ative.html interactive boiling point and
freezing point changes
Adding solute to water increases its boiling
point, the solute interacts with the water and
energy must be added to overcome the
interactions so that the water can then
change from a liquid to a gas
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http://group.chem.iastate.edu/Greenbowe/sec
tions/projectfolder/flashfiles/propOfSoln/collig
ative.html interactive boiling point and
freezing point changes
Adding solute to water decreases its freezing
point, the solute interacts with the water and
energy must be removed to overcome the
interactions so that the water can then
change from a liquid to a solid
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Thermal energy is the total energy of the
particles in a material
Thermal energy includes the kinetic energy of
the particles (their motion or vibration)
Thermal energy also includes the potential
energy of the particles (energy due to forces
acting within or between the particles)
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Heat is the name given to thermal energy
that moves or is transferred
In many things that you read, heat and
thermal energy are used interchangeably
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Heat moves from areas of greater heat
(more thermal energy) to areas of lesser heat
(less thermal energy)
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http://www.iun.edu/~cpanhd/C101webnotes/matter-and-energy/specificheat.html
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Temperature is the measure of the average
kinetic energy of the particles that make up
a sample of matter.
As the particles move faster, the temperature
rises
As the particles slow down, the temperature
falls
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Law of Conservation of Energy – Energy is
neither created nor destroyed. It can change
forms.
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Heat transfer follows the Law of
Conservation of Energy
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Energy transfers from areas of high energy to
areas of low energy but can neither be
created nor destroyed
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Liquid inside the thermometer is made of
molecules
As kinetic energy of molecules increases,
liquid molecules move faster and liquid
expands
Liquid rises in the tube inside the
thermometer
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Rising kinetic energy = rising liquid = rising
temperature on thermometer scale
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Heating and cooling a thermometer:
http://www.middleschoolchemistry.com/multi
media/chapter1/lesson3
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First scale developed
 Water melts/freezes at 32°F and boils at 212°F
 Salt water melts/freezes at 0°F, body
temperature was 96°F and degrees were divided
into 12s and then into 8s between these two points
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Celsius scale based on 100 degrees between
freezing and melting of water
 Water melts/freezes at 0°C and boils at 100°C
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Important scale used in most of science
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Based on a single point (absolute zero)
which is given a value of 0 degrees.
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From there, the scale increases by degrees
that are the same size as Celsius degrees.
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It is a scale that is based on energy content,
rather than on arbitrary temperature values
like the other two scales (based on water).
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Water freezes at the value 273.15 K and boils
at 373.15 Kelvin.
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0 on the Kelvin scale
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Point at which all particle motion stops
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Matter has no thermal energy at absolute
zero
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Law of Conservation of Energy – Energy is
neither created nor destroyed. It can change
forms.
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Heat transfer follows the Law of
Conservation of Energy
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Energy transfers from areas of high energy to
areas of low energy but can neither be
created nor destroyed
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Physical property of matter
Relates to a substance’s ability to absorb heat
Also called specific heat
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Specific heat capacity of a substance is the
amount of energy (Joules) required to raise
the temperature of 1 gram of the substance
by 1 °C
Specific heat capacity =
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Objects with low specific heat capacities heat
up more quickly than objects with high
specific heat capacities.
It takes less energy to raise their
temperatures
They also transfer their heat more quickly so
they cool down faster
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Water has a fairly high specific heat capacity,
4.184 J/g °C
This means it takes a lot of energy to raise
the temperature of water 1 °C compared to
the amount of energy it takes to heat
something with a lower specific heat capacity
Example: Iron (0.45 J/g °C) needs much less
energy to change its temperature
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Objects with low specific heat capacities are
better conductors of heat
Objects with high specific heat capacities are
better insulators because they don’t heat up
as quickly
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An insulated container that prevents a
chemical reaction from gaining heat from its
surroundings or losing heat to its surroundings
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Calorimeter experiments to calculate specific
heat capacities of objects use the Law of
Conservation of Energy and the known
specific heat capacity of water
When a heated object is placed in a cup of
cold water, the heat will move from the
object to the water
When the temperature stops changing, the
temperature of the object and water are
now the same
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When the temperature stops changing, the
temperature of the object and water are
now the same
Energy transferred to the water is equal to
the energy transferred from the object
Calculations:
Known:
Specific heat capacity of water = 4.184 J/g °C
Energy transferred to water =
mass of water (g) x Temp change (°C) x 4.184 J/g °C
Specific heat capacity of object =
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p. 22 heating and cooling gas in a bottle
http://www.middleschoolchemistry.com/multi
media/chapter1/lesson5
p. 24 heating and cooling a metal ball
http://www.middleschoolchemistry.com/multi
media/chapter1/lesson4