Lesson 13_1.ppt This will be the lesson of about volcanoess

just a lesson about

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Chapter 13
States of Matter
13.1 The Nature of Gases
13.2 The Nature of Liquids
13.3 The Nature of Solids
13.4 Changes of State

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What factors most strongly affect the
weather?
CHEMISTRY & YOU
The atmosphere is a
gas, and the factors
that determine the
behavior of gases—
temperature and
pressure—affect the
weather in the
atmosphere.

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Kinetic Theory and a Model Kinetic Theory and a Model
for Gasesfor Gases
Kinetic Theory and a Model for Gases
What are the three assumptions of
the kinetic theory as it applies to
gases?

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The word kinetic refers to motion.
Kinetic Theory and a Model Kinetic Theory and a Model
for Gasesfor Gases
•The energy an object has because of its
motion is called kinetic energy.

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The word kinetic refers to motion.
Kinetic Theory and a Model Kinetic Theory and a Model
for Gasesfor Gases
•The energy an object has because of its
motion is called kinetic energy.
•According to the kinetic theory, all matter
consists of tiny particles that are in constant
motion.
•The particles in a gas are usually molecules
or atoms.

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Kinetic Theory and a Model Kinetic Theory and a Model
for Gasesfor Gases
The kinetic theory as it applies to gases
includes the following fundamental
assumptions about gases.
The particles in a gas are considered to be
small, hard spheres with an insignificant
volume.
–Within a gas, the particles are relatively far apart
compared with the distance between particles in a
liquid or solid.
–Between the particles, there is empty space.
–No attractive or repulsive forces exist between the
particles.

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Bromine
molecule
Kinetic Theory and a Model Kinetic Theory and a Model
for Gasesfor Gases
The kinetic theory as it applies to gases
includes the following fundamental
assumptions about gases.
The motion of particles
in a gas is rapid,
constant, and random.
–Gases fill their containers
regardless of the shape and
volume of the containers.
–An uncontained gas can spread
out into space without limit.

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Kinetic Theory and a Model Kinetic Theory and a Model
for Gasesfor Gases
The kinetic theory as it applies to gases
includes the following fundamental
assumptions about gases.
The motion of particles
in a gas is rapid,
constant, and random.
–The rapid, constant motion of
particles in a gas causes
them to collide with one
another and with the walls of
their container.

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Kinetic Theory and a Model Kinetic Theory and a Model
for Gasesfor Gases
The kinetic theory as it applies to gases
includes the following fundamental
assumptions about gases.
The motion of particles
in a gas is rapid,
constant, and random.
–The particles travel in straight-
line paths until they collide with
another particle.
–The particles change direction only
when they rebound from collisions.

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Kinetic Theory and a Model Kinetic Theory and a Model
for Gasesfor Gases
The kinetic theory as it applies to gases
includes the following fundamental
assumptions about gases.
All collisions between particles in a gas are
perfectly elastic.
–During an elastic collision, kinetic energy is
transferred without loss from one particle to another.
–The total kinetic energy remains constant.

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Describe an elastic collision between
gas molecules.

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Describe an elastic collision between
gas molecules.
An elastic collision is one in which kinetic
energy is transferred from one particle to
another with no overall loss of kinetic
energy.

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Gas PressureGas Pressure
Gas Pressure
How does kinetic theory explain
gas pressure?

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Gas PressureGas Pressure
Gas pressure results from the force
exerted by a gas per unit surface area of
an object.
•Moving bodies exert a force when they collide
with other bodies.

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Gas PressureGas Pressure
Gas pressure is the result of billions of
rapidly moving particles in a gas
simultaneously colliding with an object.

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Gas PressureGas Pressure
•If no particles are present, no collisions can
occur. Consequently, there is no pressure.
•An empty space with no particles and no
pressure is called a vacuum.
Gas pressure is the result of billions of
rapidly moving particles in a gas
simultaneously colliding with an object.

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Gas PressureGas Pressure
Air exerts pressure on Earth because
gravity holds the particles in air within
Earth’s atmosphere.
•The collisions of atoms and molecules in
air with objects results in atmospheric
pressure.
•Atmospheric pressure decreases as you
climb a mountain because the density of
Earth’s atmosphere decreases as the
elevation increases.

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Gas PressureGas Pressure
A barometer is a device that is used to
measure atmospheric pressure.
•At sea level, air exerts
enough pressure to
support a 760-mm
column of mercury.
•On top of Mount
Everest, at 9000 m, the
air exerts only enough
pressure to support a
253-mm column of
mercury.
Vacuum
Atmospheric
pressure
760 mm Hg
(barometric
pressure)
253 mm Hg
Sea level On top of Mount
Everest

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When weather forecasters state that a low-
pressure system is moving into your region,
it usually means that a storm is coming.
What do you think happens to the column of
mercury in a barometer as a storm
approaches? Why?
CHEMISTRY & YOU

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When weather forecasters state that a low-
pressure system is moving into your region,
it usually means that a storm is coming.
What do you think happens to the column of
mercury in a barometer as a storm
approaches? Why?
CHEMISTRY & YOU
When a storm approaches, the column of
mercury goes down, indicating a decrease in
atmospheric pressure.

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Gas PressureGas Pressure
The SI unit of pressure is the pascal (Pa).
•Normal atmospheric pressure is about
100,000 Pa, that is, 100 kilopascals (kPa).
•Two older units of pressure are commonly
used.
–millimeters of mercury (mm Hg)
–atmospheres (atm)

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Gas PressureGas Pressure
One standard atmosphere (atm) is the
pressure required to support 760 mm of
mercury in a mercury barometer at 25°C.
•The numerical relationship among the three
units is
1 atm = 760 mm Hg = 101.3 kPa.
•Recall that standard temperature and
pressure (STP) are defined as a temperature
of 0°C and a pressure of 101.3 kPa, or 1 atm.

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A pressure gauge records a
pressure of 450 kPa. Convert this
measurement to
a.atmospheres
b.millimeters of mercury
Converting Between Units of Pressure
Sample Problem 13.1

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Analyze List the knowns and the unknowns.1
Sample Problem 13.1
KNOWNS UNKNOWNS
pressure = ? atm
pressure = ? mm hg
The given pressure is converted into the desired
unit by multiplying by the proper conversion
factor.
pressure = 450 kPa
1 atm = 101.3 kPa
1 atm = 760 mm Hg

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Identify the appropriate conversion factor
Calculate Solve for the unknowns.2
a.to convert kPa to atm.
b.to convert kPa to mm Hg.
1 atm
101.3 kPa
101.3 kPa
760 mm Hg
Sample Problem 13.1

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Multiply the given pressure by the
conversion factor.
Calculate Solve for the unknowns.2
b. 450 kPa × = 3400 mm Hg
= 3.4 × 10
3
mm Hg
101.3 kPa
760 mm Hg
1 atm
101.3 kPa
a. 450 kPa × = 4.4 atm
Sample Problem 13.1

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Because the first conversion factor is much
less than 1 and the second is much greater
than 1, it makes sense that the values
expressed in atm and mm Hg are
respectively smaller and larger than the
value expressed in kPa.
Evaluate Do the results make sense?3
Sample Problem 13.1

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What is the pressure in millimeters of
mercury inside a vacuum?

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What is the pressure in millimeters of
mercury inside a vacuum?
0 mm Hg

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Kinetic Energy and Kinetic Energy and
TemperatureTemperature
Kinetic Energy and Temperature
What is the relationship between the
temperature in kelvins and the
average kinetic energy of particles?

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Kinetic Energy and Kinetic Energy and
TemperatureTemperature
As a substance is heated, its particles
absorb energy, some of which is stored
within the particles.
•This stored portion of the energy, or potential
energy, does not raise the temperature of the
substance.
•The remaining absorbed energy does speed
up the particles, that is, increases their kinetic
energy.
–This increase in kinetic energy results in an
increase in temperature.

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Kinetic Energy and Kinetic Energy and
TemperatureTemperature
Average Kinetic Energy
The particles in any collection of atoms
or molecules at a given temperature
have a wide range of kinetic energies.
•Most have kinetic energies somewhere in the
middle of this range.
•We use average kinetic energy when
discussing the kinetic energy of a collection of
particles in a substance.

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Kinetic Energy and Kinetic Energy and
TemperatureTemperature
Average Kinetic Energy
At any given temperature, the particles of
all substances, regardless of physical
state, have the same average kinetic
energy.

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The figure below shows the distribution of
kinetic energies of water molecules at two
different temperatures.
Interpret Graphs
•The green curve
shows the distribution
of kinetic energy in
cold water.
•The purple curve
shows the distribution
of kinetic energy in hot
water.

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The figure below shows the distribution of
kinetic energies of water molecules at two
different temperatures.
Interpret Graphs
•Most of the molecules
have intermediate
kinetic energies, close
to the average value.
•Notice that the
molecules at the
higher temperature
have a wider range of
kinetic energies.

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Kinetic Energy and Kinetic Energy and
TemperatureTemperature
Average Kinetic Energy
The average kinetic energy of the
particles in a substance is directly related
to the substance’s temperature.
•An increase in the average kinetic energy of
the particles causes the temperature of a
substance to rise.
•As a substance cools, the particles tend to
move more slowly, and their average kinetic
energy decreases.

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Kinetic Energy and Kinetic Energy and
TemperatureTemperature
Average Kinetic Energy
Absolute zero (0 K, or –273.15
o
C) is the
temperature at which the motion of
particles theoretically ceases.
•No temperature can be lower than absolute
zero.
•Absolute zero has never been produced in
the laboratory.
–A near-zero temperature of about 0.000 000 000 1 K,
which is 0.1 nanokelvin, has been achieved.

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Kinetic Energy and Kinetic Energy and
TemperatureTemperature
Average Kinetic Energy
The coldest temperatures recorded
outside the laboratory are from space.
•Astronomers used a
radio telescope to
measure the
temperature of the
boomerang nebula.
•At about 1 K, it is
the coldest known
region of space.

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Kinetic Energy and Kinetic Energy and
TemperatureTemperature
Average Kinetic Energy and Kelvin
Temperature
The Kelvin temperature of a
substance is directly proportional to
the average kinetic energy of the
particles of the substance.

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What is the result of increasing the
temperature of a gas sample?
A.A decrease in the average kinetic
energy of the sample
B.No effect on the sample
C.An increase in the average kinetic
energy of the sample
D.The particles slow down.

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What is the result of increasing the
temperature of a gas sample?
A.A decrease in the average kinetic
energy of the sample
B.No effect on the sample
C.An increase in the average kinetic
energy of the sample
D.The particles slow down.

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Key ConceptsKey Concepts
Particles in a gas are considered to be small,
hard spheres with an insignificant volume.
The motion of the particles in a gas is rapid,
constant, and random. All collisions between
particles in a gas are perfectly elastic.
Gas pressure is the result of billions of
rapidly moving particles in a gas
simultaneously colliding with an object.
The Kelvin temperature of a substance is
directly proportional to the average kinetic
energy of the particles of the substance.

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Glossary TermsGlossary Terms
•kinetic energy: the energy an object has
because of its motion
•kinetic theory: a theory explaining the states of
matter, based on the concept that all matter
consists of tiny particles that are in constant
motion
•gas pressure: results from the force exerted by
a gas per unit surface area of an object; due to
collisions of gas particles with the object

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Glossary TermsGlossary Terms
•vacuum: a space where no particles of matter
exist
•atmospheric pressure: the pressure exerted
by atoms and molecules in the atmosphere
surrounding Earth, resulting from collisions of
these particles with objects
•barometer: an instrument used to measure
atmospheric pressure

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Glossary TermsGlossary Terms
•Pascal (Pa): the SI unit of pressure
•standard atmosphere (atm): a unit of
pressure; it is the pressure required to support
760 mm of mercury in a mercury barometer at
25°C

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END OF 13.1END OF 13.1