CHE 112 MODULE 1

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CHE 112 - MODULE 1

• CHAPTER 12
• LECTURE NOTES

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Properties of Gases

• Gases completely fill their container in a
  uniform manner
• Gases are compressible
• Gases have low densities
• Gases will exert pressure as the gas molecules
  collide with the inner surfaces of their
  container

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Kinetic Molecular Theory of Gases

• A gas is composed of particles that are very
  small compared with the average distance between
  the individual particles.
• Gas particles are in constant straight line,
  random motion.
• Collisions are elastic.
• Attractions between particles are negligible.
• The average kinetic energy (energy of motion) of
  these particles is directly proportional to the
  temperature in Kelvin.

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Boyles Law

• P ? 1/ V PV k when T is constant
• P pressure V volume
• The pressure is inversely proportional to the
  volume.
• As the pressure increases, the volume decreases
  and as the pressure decreases, the volume
  increases.
• P1V1 P2V2

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Charles Law

• V ? T V kT when P is constant
• V volume T temp in Kelvin
• The volume is directly proportional to the
  temperature.
• As the temp increases, the volume increases and
  as the temp decreases, the volume decreases.
• V1/T1 V2/T2

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Combined Gas Law

• Combination of Boyles and Charles Laws
• P1V1 / T1 P2V2 / T2
• Used when all the conditions of the same gas
  changes, and nothing remains constant.

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Avogadros Law

• The molar volume is defined as the volume of 1
  mole 22.4 L for any gas at Standard Temperature
  and Pressure (STP)
• STP means 273.15K (0C) and 1 atm (760mm Hg)

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Ideal Gas Law

• PV nRT
• P pressure (atm)
• V volume (L)
• n number of moles (mol)
• R gas constant 0.08206 (Latm/molK)
• T temperature (K)

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Real Gas Law

• As temperatures and pressures deviate from STP,
  the Ideal Gas Law no longer holds true.
• The Van der Waals equation is used to compensate
  for intermolecular forces and molecular volume in
  non-ideal conditions.
• (Pan/V2)(V-bn) nRT

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CHE 112 - MODULE 1

• CHAPTER 13
• LECTURE NOTES

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Intermolecular Forces

• Dipole-dipole interactions
• polar molecules attract by charge
• Dipole-induced dipole forces
• a dipole can be induced by a polar species
• London dispersion forces
• momentary attraction of non-polar molecules
• Hydrogen bonding
• attraction of H-O, H-N and H-F with other highly
  electronegative atoms

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Water and Hydrogen Bonding

• The O of a water molecule attaches to four other
  water molecules
• The hydrogen bonded water creates a tetrahedral
  of H around the O
• Water freezes into a water lattice that is
  ordered and has spaces within the repeated
  lattice crystal

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DNA and Hydrogen Bonding

• Deoxyribonucleic acid (DNA) is a chain of
  phosphates linked to sugars
• Bonded to each sugar is either a thymine,
  guanine, cytosine, or adenine base molecule
• The base molecules on one chain interact through
  hydrogen bonding with base molecules on another
  chain
• This pairing of chains produces the double helix
  of DNA

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Properties of Liquids

• Vaporization ?Hvap standard molar heat of
  vaporization
• liquid ? gas, endothermic process
• liquid ? vapor, vapor pressure
• boiling point
• Surface tension - energy to break the surface
• Capillary action - adhesive forces
• Viscosity - resistance to flow

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Vapor Pressure

• Vapor pressure the partial pressure of the
  vapor over the liquid, measured at equilibrium
• As surface molecules gain sufficient KE, they
  escape the liquid into vapor above the liquid
• As the of vapor molecules increase, more
  collisions will occur above the liquid
• More molecules will collide at the surface and
  condense back into the liquid state
• Rate of condensation rate of vaporization
• At this point, the partial pressure exerted
  vapor pressure of the liquid
• As the temperature ?, KE ?, vapor pressure?

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Boiling Point

• Boiling point the temperature at which the
  vapor pressure of a liquid the vapor pressure
  exerted on the liquid
• As temperature ?, vapor pressure ? when the
  vapor pressure atmospheric pressure, stable
  bubbles of vapor form
• The liquid begins to boil
• Once boiling begins, it will continue to boil as
  long as heat is supplied or until all the liquid
  has been converted to vapor

At 1atm, water will boil at 100C, but at the
top of Whiteface, water will boil at a lower
temperature
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Types of Solids

• Ionic compounds
• Metallic materials
• Molecular compounds
• Network solids
• Amorphous materials

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Crystalline vs Amorphous

• Crystalline has a defined structure
• Amorphous random (undefined structure)

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Cubic Units

• Simple cube
• Face-centered cube
• Body centered cube

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Phase Diagrams

• Phase Diagram shows all the phases of matter and
  their relationships for different types of matter
• Solid
• Liquid
• Gas
• Triple point
• Critical point

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Changes of States

• Melting (solid gt liquid)
• Freezing (liquid gt solid)
• Vaporization (liquid gt vapor)
• Condensation (vapor gt liquid)
• Sublimation (solid gt vapor)
• Condensation by deposition (vapor gt solid)

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CHE 112 - MODULE 1

• CHAPTER 14
• LECTURE NOTES

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Units of Concentration

• Molarity (M) moles of solute
• Liters of solution
• Molality (m) moles of solute
• Kg of solvent
• Mole fraction (XA) moles of A
• moles of
  solution

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Units of Concentration (cont.)

• Weight A mass of A X 100
• total mass
• Parts per million (ppm) 1g of matter
• mass
  million g
• 1ppm 1mg/L 1?g/ml

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Solutions

• Saturated - solution containing the maximum
  amount of dissolved solvent
• Unsaturated - Less than saturated
• Supersaturated - more than saturated

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Liquid/Liquid Interaction

• Miscible - liquids that mix well due to like
  polarity
• Immiscible - liquids that do not mix because one
  is polar and the other is non-polar
• Likes dissolve likes

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Solids Dissolved in Liquids

• Hydrated - ionic solids dissolve when surrounded
  by polar water molecules in solution
• Heat of Solution (?Hsoln) net energy change for
  the solution process
• Exothermic rxn yield more soluble cmp
• Endothermic rxn yield insoluble cmp

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Enthalpy of Hydration

• The energy involved with hydrating an ion depends
  on 3 things
• distance between the ion dipole (closer the
  stronger attraction)
• charge on the ion (higher the stronger)
• polarity of the solvating molecule (greater the
  magnitude of the dipole the stronger)

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Vapor Pressure Lowering

• VPL a colligative property (concentration
  dependent) equal to the vapor pressure of pure
  solvent minus the vapor pressure of the solution
• Occurs when a nonvolatile solute is mixed with a
  solvent that have similar structure
• ?Psolv Psolv - ?Psolv

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Raoults Law

• Psolv XsolvP ?solv
• Psolv ? Xsolv
• Vapor pressure of the solution is lower than the
  that of the pure solvent
• CD-ROM Screen 14.7
• ?Psolv -XsolvP?solv

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Freezing Point Depression

• Freezing point depression is a colligitive
  property equal to the freezing point of the pure
  solvent minus the freezing point of the solution
• ?Tfp kfp msolute
• ?Tfp freezing point depression
• kfp freezing point depression constant (for
  water it is -1.86C/m)
• msolute molal concentration

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Boiling Point Elevation

• Boiling point elevation is a colligitive property
  equal to the boiling point of the solution minus
  the boiling point of the pure solvent
• ?Tbp kbp msolute
• ?Tbp boiling point elevation
• kbp boiling point elevation constant (for water
  it is 0.512C/m)
• msolute molal concentration

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Colloids

• Dispersion of particles of one substance
  (dispersed phase) throughout another substance or
  solution (the continuous phase)
• Appears homogeneous
• Particle sizes are between 10 2000 angstroms
  (1x10-10m) in diameter

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Micelle

• Aggregate of molecules that have a polar end and
  a nonpolar end.
• Nonpolar ends will meet together in the middle,
  while the polar ends will be attracted outward
  toward the water molecules

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