Chapter 10, Section 4 Phase Diagrams and Sublimation

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Chapter 10, Section 4Phase Diagrams and
Sublimation

• Sarah Celia, Briana Philips, Michelle Delong,
  Jenna Ciccarelli, and Laura Amoroso

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What is Sublimation?

• Definition
• The changing of a solid substance directly to a
  vapor without turning to a liquid first
• Also used to describe the reverse process of gas
  changing directly to the solid again upon cooling

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Sublimation

• Examples
• Most common example is that of dry ice
• When dry ice is exposed to the air, it begins to
  sublimate, or change to vapor.

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Sublimation

• Examples (contd)
• When iodine, on being heated, changes from a dark
  solid to a purplish vapor that condenses directly
  to a crystalline solid upon striking a cool
  surface 

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Sublimation

• Sublimation also occurs when air saturated with
  water is suddenly cooled to a temperature below
  the freezing point of water
• Frost and snowflakes are formed by the water
  changing directly from the gaseous to the solid
  state

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Evaporation vs. Sublimation

• Sublimation is what happens when a frozen
  material changes to gaseous form
• Evaporation is what happens when a liquid changes
  to a vapor

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Picture - Sublimation

• This is a drawing of what the surface of a comet
  might look like when sublimating.

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Picture - Sublimation
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Picture - Sublimation
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Phase Diagrams

• The textbook definition of a phase diagram is A
  diagram that gives the conditions of temperature
  and pressure at which a substance exists as a
  solid, liquid, or gas (vapor)

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Phase Diagrams
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Phase Diagrams

• Shows the phases in different sections of the
  diagram
• The meeting point of all three lines on the
  diagram is called the triple point
• The triple point describes the only set of
  conditions at which all three phases can exist in
  equilibrium

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Phase Diagrams

• The critical point is the place on the diagram
  where it is not possible to distinguish between
  the gas and liquid phases of an element

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Phase Diagrams

• Using a phase diagram, you can determine the
  changes in the melting point and boiling point of
  a substance with changes in external pressure.

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Phase Diagrams

• Eutectic point- defines the point where a
  eutectic reaction takes place
• May be none, one, or more than one on a phase
  diagram
• Eutectic reaction- reaction where one solid is
  formed into two completely new solids

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Phase Diagrams
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Reference

• http//www.soton.ac.uk/pasr1/build.htm
• http//www.chm.davidson.edu/ChemistryApplets/Phase
  Changes/PhaseDiagram.html
• http//www.windows.ucar.edu/tour/link/comets/subl
  imation.html
• http//www.infoplease.com/ce6/sci/A0847062.html
• http//cosmos.swin.edu.au/entries/sublimation/subl
  imation.html?e1
• http//www.physique.ens-cachan.fr/laboratoire/expe
  riences/expdetail.php?IDE41
• http//en.wikipedia.org/wiki/ImagePhase-diag.svg
• http//www.fphoto.com/stockindex2006/32779302C-2RM
  .jpg
• http//www.mkicorp.com/includes/contents/apps/imag
  es/sublimation1.jpg
• Textbook

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Acknowledgements

• We would like to thank Mr. Edsall for giving us
  time to work on this project in the library.