Modern Chemistry Chapter 10 States of Matter

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Modern Chemistry Chapter 10States of Matter
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Kinetic-Molecular Theory

• The kinetic-molecular theory of matter is based
  on the idea that particles of matter are always
  in motion and this motion has consequences that
  affect its physical properties.

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Kinetic-Molecular Theory of Gases

• 1- Gases consist of large numbers of tiny
  particles that are far apart relative to their
  size.
• 2- Collisions between gas particles and between
  particles and their container walls are elastic.
  An elastic collision is one in which there is no
  net loss of total kinetic energy.
• 3- Gas particles are in continuous, rapid,
  random motion. They therefore possess kinetic
  energy (energy in motion).
• 4- There are no forces of attraction between gas
  particles.
• 5- The temperature of a gas depends upon the
  average kinetic energy of the particles of the
  gas.

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Gases have indefinite shape and indefinite
volume.
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The Kinetic-Molecular Theory and the Nature of
Gases

• EXPANSION- Gases do not have definite shape or
  volume. They expand to completely fill any
  container.
• FLUIDITY- Gases flow so they are fluids.
• LOW DENSITY- The density of a gas is about
  1/1000 that of the same substance in the liquid
  state.
• COMPRESSIBILITY- Gases can be compressed (the
  volume decreases) by applying pressure to the
  gas.
• DIFFUSION- Gases have the ability to spread and
  mix with one another due to the random motion of
  their particles.
• EFFUSION- A process by which gas particles under
  pressure pass through a tiny opening from one
  container to another.

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Section 2- LIQUIDS

• A LIQUID is a substance that has definite volume
  but indefinite shape (it takes the shape of its
  container).
• Liquids are fluids because they have the ability
  to flow from one container to another and take
  the shape of the new container.

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Properties of Liquids

• 1- Liquids have a high density relative to
  gases. Their density is about 1000 x that of the
  gas of the same substance.
• 2- Liquids are relatively not compressible.
• 3- Liquids have the ability to diffuse.
• 4- Liquids exhibit surface tension, a force that
  tends to pull adjacent parts of a liquids
  surface together, thereby decreasing the surface
  area to its smallest possible size. Surface
  tension resists penetration of objects into a
  liquid.
• 5- Liquids have capillary action, the attraction
  of the surface of a liquid to the surface of a
  solid.

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Changes of Physical State

• vaporization is the process by which a boiling
  liquid changes to a gas
• evaporation is the process by which particles
  escape from the surface of a non-boiling liquid
  and enter the gas state
• boiling is the change of a liquid to bubbles of
  vapor that appear throughout the liquid
• freezing (solidification) is the physical change
  of a liquid to a solid by the removal of heat
  energy

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Section 3SOLIDS

• solids have a definite shape and a definite
  volume
• crystalline solids consist of crystals, a
  substance in which the particles are arranged in
  an orderly, geometric, repeating pattern
• amorphous solids consist of particles that are
  randomly arranged

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Properties of Solids

• 1- DEFINITE SHAPE VOLUME
• 2- DEFINITE MELTING POINT
• melting is the physical change from a solid to
  a liquid by the addition of heat
• melting point is the temperature at which a solid
  becomes a liquid
• supercooled liquid is a substance that retains
  certain properties of a liquid even at
  temperatures where it appears to be a solid
  (glass, plastics,)
• 3- HIGH DENSITY (10x a liquid 10,000x a gas)
• 4- INCOMPRESSIBILITY
• 5- LOW RATE OF DIFFUSION

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Crystalline Solids

• crystal structure is the total three-dimensional
  arrangement of particles of a crystal
• crystal lattice is the representation of the
  arrangement of a crystal using a coordinate
  system
• unit cell is the smallest portion of a crystal
  lattice that shows the three-dimensional pattern
  of the entire lattice

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Types of Crystals

1. ionic crystals consist of positive negative
   ions arranged in a regular pattern such as NaCl
   (salt) crystals
2. covalent network crystals consists of atoms
   covalently bonded to their adjacent atoms such as
   diamonds SiO2 (sand)
3. metallic crystals consists of metal cations
   surrounded by delocalized valence electrons
4. covalent molecular crystals consists of
   covalently bonded molecules held together by
   intermolecular forces

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Amorphous Solids

• Glass is made by cooling molten materials in a
  way that prevents them from crystallizing. This
  allows the glass to appear to be a solid yet be
  transparent.
• Other examples include plastics and
  semiconductors (used in electronics).

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Section 4- Changes of State

• 1- The three most recognized physical states of
  matter are solid, liquid, gas.
• 2- A phase is any part of a system that has
  uniform composition and properties.
• 3- When a substance changes its physical state is
  called a phase change.
• Condensation is the process by which a gas
  changes to a liquid.
• Equilibrium is a condition in which two opposing
  changes occur at equal rates (eg. liquid to gas
  gas to liquid)
• Equilibrium vapor pressure is the pressure
  exerted by a vapor in equilibrium with its
  corresponding liquid at a given temperature.
• Volatile liquids are liquids that evaporate
  easily.

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Boiling

• Boiling is the conversion of a liquid to a vapor
  (gas) throughout all parts of the liquid.
• Boiling point of a liquid is the temperature at
  which the equilibrium vapor pressure of the
  liquid equals the atmospheric pressure.
• Energy must be added continuously in order to
  keep a liquid boiling.
• Molar enthalpy of vaporization ( ?Hv ) is the
  amount of energy needed to vaporize one mole of a
  liquid at the liquids boiling point under
  constant pressure.
• Heat of vaporization is the amount of heat needed
  to vaporize one gram of a liquid at its boiling
  temperature.
• Heat of vaporization for water is 540
  calories/gram.

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Freezing Melting

• Freezing is the physical change of a liquid
  becoming a solid. Also called solidification or
  fusion.
• Freezing point is the temperature at which a
  liquid becomes a solid and the solid and the
  liquid are at equilibrium.
• Molar enthalpy of fusion ( ?Hf ) is the amount
  of energy required to melt one mole of a solid at
  its melting point.
• Heat of fusion is the amount of heat needed to
  melt one gram of a solid.
• For ice, this is 80 calories/gram.

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Other Changes of Physical State

• Sublimation is the process by which a solid
  changes to a gas, bypassing the liquid state.
• Examples include dry ice, moth balls, iodine, and
  ice at temperatures below 0C.
• Deposition is the process by which a gas changes
  directly to a solid, bypassing the liquid state.
• An example would be frost.

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Phase Diagrams

• A phase diagram is a graph of pressure versus
  temperature that shows the conditions under which
  the phases of a substance exist.
• The triple point of a substance indicates the
  temperature and the pressure conditions at which
  the solid, liquid, and vapor of the substance can
  coexist at equilibrium.
• The critical point of a substance indicates the
  critical temperature and pressure
• The critical temperature is the temperature above
  which a substance cannot exist in the liquid
  state.
• The critical pressure is the lowest pressure at
  which a substance can exist as a liquid at the
  critical temperature.
• Please see figure 16 on page 347 of the textbook.
• Use figure 16 to answer section review question
  7 on page 348 of the textbook.

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Section 5- Water

• Hydrogen bonding in water molecules make water a
  unique substance. Without hydrogen bonding,
  water would be a gas at room temperature.
• Hydrogen bonding allows water to form crystals
  when it freezes.
• Due to the crystal structure of ice, it is less
  dense than liquid water and will float.
• Floating ice acts as insulation to water below.
• If ice sank rather than floated, water would turn
  to solid ice in temperate climates and most of
  the living organisms in the water would die. Can
  you say frozen fish sticks?

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Water

• Water freezes at 0C and boils at 100C.
• The molar enthalpy of fusion for water is 6.009
  kJ/mol at one atmosphere of pressure.
• The molar enthalpy of vaporization for water is
  40.79 kJ/mol at one atmosphere of pressure.
• Do practice problems 1 2 on page 351.

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Questions about water.

1. Why are there more orchards, vineyards, and
   vegetable farms near Lake Erie than in central
   Ohio?
2. Why does steam cause more severe burns than
   boiling water?
3. Why do we use ice cubes?
4. Why does snow at very low temperatures (dry snow)
   contain less water than snow that falls at
   temperatures around freezing (wet snow)?
5. Why do we say that it takes about 7 of snow to
   equal 1 of water?
6. What causes the frost on car windows?

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Chapter 10 Test Review

• 25 multiple choice questions
• definition applications of the
  kinetic-molecular theory
• why matter changes phase
• definition of temperature
• examples of gas diffusion gas effusion
• expansion compression of gases
• effects of intermolecular forces and their
  application to states of matter
• compare density the states of matter
• definitions of vaporization, evaporation,
  sublimation
• motion of the particles of a sample of matter in
  the three physical states
• properties of solids, liquids, gases
• compare crystalline vs. amorphous solids
• definitions of crystal types crystal lattice
• definitions of triple point, volatile
• factors that affect boiling
• the boiling process
• the density of ice versus water
• temperature of greatest density of water

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Honors Chemistry Chapter 10 Test

• 30 multiple choice questions
• definition applications of the
  kinetic-molecular theory
• why matter changes phase
• definition of temperature
• examples of gas diffusion gas effusion
• expansion compression of gases
• effects of intermolecular forces and their
  application to states of matter
• compare density the states of matter
• compare the energies of the phases of matter
• definitions of vaporization, evaporation,
  sublimation
• motion of the particles of a sample of matter in
  the three physical states
• properties of solids, liquids, gases
• compare crystalline vs. amorphous solids
• definitions of crystal types crystal lattice
• definitions of triple point, volatile
• factors that affect boiling
• the boiling process
• the density of ice versus water
• temperature of greatest density of water