Heating and Cooling Curves continued

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Heating and Cooling Curves continued

• Harry S Truman Chemistry Dept.

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How does kinetic energy fit on the heating curve?

• As the phase changes from solid to liquid or
  liquid to gas and entropy increases potential
  energy decreases
• As the temperature increases, so does the kinetic
  energy (T KE up)
• During the flat portions of the heating curve and
  entropy increases and so does Potential Energy.
  (?S up PE up)
• If KE increases then PE stays constant and if PE
  increases then KE stays constant.

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Which segments have an increase in KE? Which have
an increase in PE? Which have an increase in ?S?
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A few other key facts about the heating curve
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A few other key facts about the heating curve
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A few other key facts about the heating curve
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What other curves do we have besides the heating
curve?

• Cooling Curve shows the changes in phase,
  energy and temperature as a substance cools down
  over the course of time.

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What does the cooling curve look like?
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What are the parts of the cooling curve?
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What are the parts of the cooling curve?
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What are the parts of the cooling curve?
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What are the parts of the cooling curve?
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How does the cooling curve relate to the heating
curve?

• During the decline temperature is decreasing so
  kinetic energy is decreasing. (T down KE down)
• During the flat sections entropy is decreasing so
  potential energy is decreasing (?S and PE down)
• The temperature at which a sample freezes is the
  same as which it melts (TMTF)
• The temperature at which a sample boils is the
  same at which it condenses (TBTC)

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Summary

• The heating curve and cooling curve are similar
  yet opposite. They both show phase, energy and
  temperature changes, but in the cooling curve KE,
  T, PE and ?S all decrease (at different points).
  Freezing and melting both happen at the same
  temperature much like condensation and
  evaporation.

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