Phase of Matter

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Phase of Matter
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Phases of Matter

• Gases indefinite volume and shape, low density.
• Liquids definite volume, indefinite shape, and
  high density.
• Solids definite volume and shape, high density
• Solids and liquids have high densities because
  their molecules are close together.

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Temperature

• Measured in Celsius (C)
• All math is done in Kelvin (K)
• K C 273.15
• 55 C _________K
• 350 K _________C
• Standard Temp. refers to 0 C
• Absolute Zero 0 K lowest temp possible

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Kinetic Theory

• Kinetic theory says that molecules are in
  constant motion.
• Perfume molecules moving across the room are
  evidence of this.
• However, not all molecules in a sample will move
  at the same speed

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Kinetic Energy and Temperature

• Kinetic energy is the energy of motion
• Temperature is a measure of the Average kinetic
  energy of the molecules of a substance.
• Higher temperature faster molecules.
• At absolute zero (0 K) all molecular motion would
  stop.

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of Molecules
Kinetic Energy
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High temp.
of Molecules
Low temp.
Average kinetic energies are temperatures
Kinetic Energy
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Temperature

• The average kinetic energy is directly
  proportional to the temperature in Kelvin
• If you double the temperature (in Kelvin) you
  double the average kinetic energy.
• If you change the temperature from 300 K to 600 K
  the kinetic energy doubles.

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Heat

• Not the same as temperature
• Heat is the total kinetic energy of all particles
  in a substance
• Heat flows in or out of a substance until
  temperature is equalized
• Heat always flows from high to low temperature

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Heat

• Total kinetic energy of the molecules in a
  substance
• Units
• Calorie amount of heat needed to raise the temp
  of 1g of water 1?C
• Joule metric unit of heat
• 1 cal 4.186 J
• 5.75 cal __________J
• 15.5 J __________cal

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Phase Changes
Solid
Gas
Liquid
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Melting
Solid
Gas
Liquid
Freezing
Condensation
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• Heat is either added or removed during phase
  changes
• For each phase change below, will heat be
  absorbed or released. Describe as endothermic or
  exothermic.
• - freezing
• - melting
• - evaporating
• - condensing
• - sublimation
• - resublimation

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Entropy

• Disorder of particles (randomness)
• In nature all systems tend to disorder, increase
  in entropy