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Kinetic Theory and Gas Pressure

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elastic collision- no loss of kinetic energy or momentum ... http://www.aeromech.usyd.edu.au/aero/atmos/stdatm.html. Addison Wesley's Chemistry Text Book ... – PowerPoint PPT presentation

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Title: Kinetic Theory and Gas Pressure


1
Kinetic Theory and Gas Pressure
  • Grace Byrne, Mary McDyer, Mike Pileggi,
    Bernadette Smith and Tri Tran

2
Topics
  • Kinetic Theory
  • Introduction
  • Part 1
  • Part 2
  • Part 3
  • Gas Pressure
  • Barometers
  • Quiz

3
Kinetic Theory Introduction
  • Kinetic energy the energy an object has because
    of motion
  • Kinetic theory states that tiny particles in
    all forms of matter are constantly in motion

http//www.hometrainingtools.com/images/phases20o
f20matter.jpg
4
Kinetic Theory Introduction
http//hyperphysics.phy-astr.gsu.edu/hbase/kinetic
/kinthe.html
5
Kinetic Theory Part 1
  • Applied to Gases
  • Made up of objects with defined mass and no
    volume
  • Particles travel in random straight-line motion
  • All collisions are elastic, kinetic energy is
    conserved
  • Gas particles do not interact with each other or
    walls of container
  • Gas has kinetic energy proportionate to
    temperature

6
Kinetic Theory Part 1
  • Gas is composed of particles, usually molecules
    or atoms
  • Particles considered to be small hard spheres
  • Small particles relative to distance apart
  • Frequent collisions between molecules
  • Travel in straight line until collide

http//www.schulenberg.com/gifs/kinetic_theory.gif
7
Kinetic Theory Part 1
  • Each individual molecules has the standard
    physical properties of mass, momentum, and energy
  • Dmass of molecules/volume which the gas occupies
  • Pressure of gas is a measure of the linear
    momentum of the molecules
  • Force/areapressure

8
Kinetic Theory Part 1
  • Temperature of a gas is a measure of the mean of
    kinetic energy
  • The higher the temperature, the greater the
    kinetic energy

http//www.grc.nasa.gov/WWW/K-12/airplane/kinth.ht
ml
9
Kinetic Theory Part 2
  • All particles constantly move in random motion.
  • The only time that particles are not in motion is
    when they are at Absolute Zero
  • Absolute Zero temperature at which gases use no
    pressure
  • Particles move independently.
  • They do not move in groups and each particle has
    its own path

10
Kinetic Theory Part 2
  • Particles move in straight paths.
  • The only way they change direction is if they
    collide with another particle or with the side of
    the container they are in.
  • Gases fill their containers no matter its shape
    or volume.

http//www.bcpl.net/kdrews/kmt/kmtpart2.htmlPart
202
11
Kinetic Theory Part 2
  • Uncontained gases diffuse into space.
  • If a gas is contained it will expand to fill the
    volume or leave the container.
  • Gases should diffuse to the point of even
    distribution, but cant because of effects of the
    environment.

http//www.bcpl.net/kdrews/kmt/kmtpart2.htmlPart
202
12
Kinetic Theory Part 3
  • The particles collide elastically.
  • elastic collision- no loss of kinetic energy or
    momentum
  • Energy from elastic collisions transfers from one
    object to another and no heat or sound is
    generated.
  • examples billiard balls, swinging balls


http//www.bcpl.net/kdrews/kmt/kmtpart3.htmlPart
203
http//hyperphysics.phy-astr.gsu.edu/hbase/elacol.
html
13
Kinetic Theory Part 3
  • Hard spheres are nearly elastic
  • Elastic means return exactly to original shape
  • An inelastic collision- change in kinetic energy
  • heat is generated
  • examples car crash, puddy

http//www.bcpl.net/kdrews/kmt/kmtpart3.htmlPart
203
14
Gas Pressure
  • Gas particles exert small amounts of force when
    they are alone
  • Many collisions of gas particles occurring at the
    same time produce measurable amounts of force
  • Gas pressure is the result of simultaneous
    collisions of a number of gas particles on an
    object

15
Gas Pressure
  • Gas pressure - the force exerted by a gas per
    unit surface area of an object
  • If no gas particles are present , then there is
    no pressure
  • Vacuum - the empty space with no gas particles

16
Gas Pressure
  • Air exerts pressure on earth because of gravity
    holding air in Earths atmosphere
  • Atmospheric pressure results from collisions of
    air molecules with objects
  • As elevation increases, atmospheric pressure
    decreases because of thinning air
  • Barometers measure atmospheric pressure

17
Units of Pressure
  • Pascal (Pa) the SI unit of pressure
  • Two older units of measure are
  • Millimeters of mercury (mm Hg)
  • And atmospheres (atm)

18
Standard Atmosphere (atm)
  • Standard Atmosphere (atm)
  • A unit of pressure
  • The pressure required to support 760 mm of
    mercury in a mercury barometer at 25 C.

19
Converting atm to Pa
  • 1 atm 1.01325 Pa
  • Atm- standard atmosphere
  • Pa- pascal
  • 1.01325 the standard condition of pressure of 1
    atm

20
How Barometers Work
  • A straight glass tube filled with mercury and
    closed at one end
  • The tube was placed in a dish of mercury so that
    the open end was below the surface of the mercury
    in the dish.
  • The height of mercury in the tube depends on the
    pressure created by collisions of air molecules
    with the surface of the mercury in the dish

21
http//www.atmos.washington.edu/2005Q3/101/LINKS-h
tml/MercuryBarometer.jpg
22
Quiz
  • 1. The kinetic energy of a gas is ________ to the
    temperature.
  • a. Proportional b. Disproportional c.
    Not Related
  • 2. Gas particles travel in straight paths until
    they ________. a. combust b. disappear c.
    collide
  • 3. The higher the temperature the ________ the
    kinetic energy. a. less b. greater c. they
    are equal
  • 4. Gases fill their containers no matter its
    ______or volume. a. shape b. temperature
    c. neither
  • 5. The temperature at which gases use no pressure
  • a. Absolute Zero b. boiling point c.
    freezing

23
Quiz
  • 6. Gas particle collide __________.
  • a. they dont collide b. elastically c.
    reflectively
  • 7. The force exerted by a gas per unit surface
    area of an object
  • a. Gas pressure b. pressure leak c. air
    pressure
  • 8. The empty space with no gas particles is
  • a. vacuum b. black hole c. duster
  • 9. _________ measure atmospheric pressure.
  • a. Thermometer b. Barometer c. calorimeter
  • 10. What element is used in barometers?
  • a. Mercury b. Iron c. Copper

24
Bibliography
  • http//www.answers.com/topic/absolute-zero
  • http//www.bcpl.net/kdrews/kmt/kmt.html
  • http//www.grc.nasa.gov/WWW/K-12/airplane/kinth.ht
    ml
  • http//www.schulenberg.com/gifs/kinetic_theory.gif
  • http//hyperphysics.phy-astr.gsu.edu/hbase/elacol.
    html
  • http//www.launc.tased.edu.au/online/sciences/phys
    ics/elas.htm
  • http//www.iadeaf.k12.ia.us/Momentum.htm
  • http//hyperphysics.phy-astr.gsu.edu/hbase/kinetic
    /kinthe.html
  • http//comp.uark.edu/jgeabana/mol_dyn/
  • http//www.bom.gov.au/info/aneroid/aneroid.shtmlme
  • http//www.physics.nist.gov/Pubs/SP811/appenB.html
  • http//www.aeromech.usyd.edu.au/aero/atmos/stdatm.
    html
  • Addison Wesleys Chemistry Text Book
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