Boiling Point Chapter 10 Section 2

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Boiling PointChapter 10 Section 2

• Brendan Gower, Jenna Moran, Jaclyn Mullen,
  Jessica Saddler, Rachel Randazzo

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Points that we will cover

• Intermolecular Forces
• Kinetic Energy
• Boiling Point
• Vaporization
• Vapor Pressure
• Boiling as a cooling process

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Intermolecular Forces

• Intermolecular Forces ionic forces that occur
  as a result of opposite charges being attracted
  to one another.
• Liquid particles are attracted to one another by
  intermolecular forces which refers to boiling
  point.

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Continued

• Liquid particles are polar, meaning the poles of
  their molecules are oppositely charged and
  attracted to one another.
• This causes a liquid to have a unified, flowing
  form.

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Kinetic Energy

• Particles of a liquid that are constantly in
  motion always have kinetic energy.
• Kinetic energy energy of motion
• Non-heated liquid particles do not contain enough
  kinetic energy to allow them to escape the liquid
  as vapor.

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Continued

• When heat is added to a liquid, kinetic energy is
  added to the liquid particles.
• This causes them to move more quickly.
• Heating also weakens the intermolecular forces
  causing them to become less attracted to one
  another.

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Continued

• Heat and kinetic energy have a direct
  relationship.
• They increase and decrease together.
• More heatfaster moving particlesmore kinetic
  energyhigher temperature

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What is Boiling Point?

• Definition the temperature at which the vapor
  pressure of the liquid is just equal to the
  external pressure.
• Normal boiling point the boiling point of a
  liquid at a pressure of 101.3kPa (kilopascals-
  the SI unit used to measure pressure)
• Water 100C

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Vaporization - the conversion of a liquid to a
gas or vapor.

• When a liquid reaches its boiling point, the
  particles escape the liquid in the form of
  bubbles of vapor (gas).
• This occurs because the kinetic energy causes the
  particles to move so fast that they actually
  vaporize.
• The gas bubbles are less dense than the liquid,
  so thats why you see bubbles when you boil
  something!

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Vapor Pressure and External Pressure

• Definition - A force do to gas above the liquid.
• Pressure decrease boiling point/temperature
  decrease
• Pressure increase boiling point/temperature
  increase
• The external pressure (atmospheric pressure) must
  be equal to the vapor pressure (a pressure
  produced from the gas above the liquid).

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At the boiling point, the vapor pressure is equal
to atmospheric pressure, bubbles form, and the
vaporization becomes a volume phenomena.
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Examples

• Open books to page 278
• Sea Level at 70C liquid does not boil
• Sea Level 100C liquid boils
• Atop Mount Everest 70C liquid boils
• Chart of normal boiling points for common
  substances

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Boiling as a Cooling Process

• In a boiling liquid the particles with the
  highest kinetic energy escape first.
• The particles with the least kinetic energy are
  left in the liquid state.
• The leftover particles are moving slower and
  therefore the temperature decreases.

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Cooling Process

• Adding more heat to the liquid allows more
  particles to vaporize, but the temperature cannot
  rise above its boiling point.
• If heat is supplied at a greater rate, the liquid
  only boils faster.

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• Lets take a look at the Boiling Process!

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THE END!
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Acknowledgements

• Wed like to thank ?
• Our moms for driving us to each others houses
• Mr. Edsall for teaching us about boiling point
  and the movement of particles
• Our group for helping to finish the project
• The class for listening and paying attention

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Works Cited

• Wilbraham, Antony C., Dennis D. Staley, Michael
  S. Matta, and Edward L. Waterman. Chemistry.
  Needham, Upper Saddle River, Glenview Prentice
  Hall, 2002.
• Hyperphysics. August 2004. Georgia State
  University Department of Physics and Astronomy.
  30 January 2007. .edu/hbase/kinetic/vappre.html
• Boiling. 30 January 2007. edu/gchelp/liquids/boil.html
• Vapor Pressure and Boiling Point. 2 February
  2007. e_Boiling_Point.htm

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Quiz

• 1. When temperature rises, the water particles
• a. Move faster b. Move slower c. stop moving
• 2. If vapor pressure decreases, what will happen
  to the boiling point?
• a. increase b. decrease c. stay the same

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Quiz

• 3. What is energy of motion?
• a. Kinetic energy b. potential energy c. solar
  energy
• 4. What is the boiling point of water?
• a. 500C b. 100C c. 1234C

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Quiz

• 5. What is the temperature at which the vapor
  pressure of the liquid is just equal to the
  external pressure?
• a. Kinetic energy b. boiling point c. molecules
• True/False
• 6. ___ Water molecules are attracted to each
  other.

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Quiz

• 7. ___ Boiling is actually a cooling process.
• 8. ___ External pressure does not affect the
  boiling point.

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Quiz

• 9. The bubbles that form when a liquid is boiled
  are
• a. vapor bubbles b. smoke bubbles c. molecule
  bubbles
• 10. What is the conversion of a liquid to a gas
  or vapor?
• a. force b. heat c.
  vaporization

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Answers

• A
• B
• A
• B
• B

• 6. T
• 7. T
• 8. F
• 9. A
• 10.C