Phase ChangesAny time the state of matter changes, intermolecular forces are created or destroyedThis requires energy (think temperature or pressure).

Phase ChangesEvaporation vs. BoilingEvaporation occurs when particles at the surface of a liquid become a gas.[http://wps.prenhall.com/wps/media/objects/476/488316/Instructor_Resources/Chapter_12/FG12_11.JPG]

Phase ChangesBoiling occurs when particles throughout the liquid become a gas[http://whatscookingamerica.net/Foto4/BoilingWater.bmp]

[http://wps.prenhall.com/wps/media/objects/602/616516/Media_Assets/Chapter10/Text_Images/FG10_12.JPG]Boiling causes liquid to gas conversion to occur faster.

Heating CurveGraph that shows temperature of a substance over time.Plateaus represent two phases present.Click here for an animation[http://dbhs.wvusd.k12.ca.us/webdocs/NChO/NChO-92-Local-30.GIF]

[http://www.bbc.co.uk/schools/ks3bitesize/science/images/sci_dia_21.gif]or condensingor freezingHeating Curve For H2O

Phase Changes & Thermoq = (m)(s)(T)But T = 0 during a phase changeHeat (q) is still being added so a different equation is needed.

Phase Changes & Thermoq = (moles of substance)(Hphase change)How much energy does it take to change 54.0 g of ice to liquid water?

Phase Changes & Thermo54.0 g H2O18.0 g H2O1 mol H2O= 3.00 mol H2O First, find the moles of water:

Phase Changes & ThermoThen, plug into the equation to solve:q = (3.00 moles)(6.01 kJ/mol)q = 18.0 kJ of energy

Phase Changes & ThermoWhat if the temperature changes and the phase changes?Example:How much energy does it take to melt 108 g of ice an heat it to a temperature of 50.0oC?

Phase Changes & Thermoq = (moles)(Hfus)+ (m)(s)(T)Find the moles of water108 g H2O18.0 g H2O1 mol H2O= 6.00 mol H2O

Phase Changes & Thermo

Phase Changes & Thermoq = 36.1 kJ + 22600 JOrq = 58.7 kJ

Phase DiagramsGraph that shows how pressure and temperature affect the phases of matter.[http://cwx.prenhall.com/bookbind/pubbooks/hillchem3/medialib/media_portfolio/text_images/CH11/FG11_10.JPG]

[http://library.thinkquest.org/C006669/media/Chem/img/Graphs/Phase.gif]

[http://cwx.prenhall.com/bookbind/pubbooks/hillchem3/medialib/media_portfolio/text_images/CH11/FG11_06.JPG]

Phase DiagramsThe triple point is where all three phases of matter coexist.Click here for a video example[http://tbn0.google.com/images?q=tbn:tA2QLC4fXbJWjM:http://img.scoop.co.nz/stories/images/0611/0c994da3e92a18f9a4cb.jpeg]

Dry IceCO2 Gas