Chapter 10 – States of Matter by dffhrtcv3

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									    Chapter 10: States of Matter
• Kinetic Molecular Theory = the idea that
  particles of matter are always in motion;
  this applies to all states of matter
• Used to explain properties of matter in
  terms of energy
                 Ideal Gases
= hypothetical gas that perfectly fits all 5 assumptions of
                        the KMT:

  1) Gases consist of a large # of particles that occupy a
     larger space with respect to their relative sizes thus
     gases can be easily compressed
  2) Collisions b/t particles and walls are perfectly elastic
     ( = no loss of KE)
  3) Gas particles are in rapid, random, constant motion
  4) There are no forces of attraction b/t gas particles
  5) Temperature of a gas depends on the average
     KE of the particles; directly proportional

     A gas that is always a gas - Doesn’t exist!
The Kinetic Molecular Theory…
• Applies to only ideal gases
• Real gases act like ideal ones at low
  pressure and high temperatures – explain!
                Do Now
•   Homework: p. 336 and 341
    reading/questions

1. What is the KMT?
2. What is an ideal gas? Real gas?
3. When do these two most resemble one
   another?
4. What are some characteristics of a gas?
       Characteristics of Gases
• Expansion: no definite shape or volume; fill any
  container, regardless of shape
• Fluidity: particles slide easily over one another; act like
  liquids, thus they are both fluids
• Low Density and Compressibility: volume can be
  decreased
• Diffusion: since gases are always randomly moving,
  freely mix together w/ other gases
• Effusion: process by which gases move out of a small
  opening; molecules with low mass efuse more quickly
  than those with larger masses

                          KE= ½ mv2
 Polar gas molecules deviate from
        ideal ones at times
• Explain…
• Also, real gases do not act like real ones
  at low temps and high pressure – explain!
                       Liquids
• Least common state of
  matter in universe; not so
  on Earth
• Operate at slim range of
  temps/pressures
• Volume, shape, density?
• Particles in constant
  motion, and closer than
  those of a gas (d/t
  intermolecular forces
Other Characteristics of liquids:
• They have a very high density when
  compared to gases; depends on
  temperature  lower temp…
  except for water
• Not easily compressed
• Easily diffuse in other liquids it can
  dissolve in d/t… much slower than it is in
  gases – why?
                 Surface Tension
• All liquids exhibit surface
  tension = a force that tends to
  pull adjacent particles at a
  liquids surface together,
  decreasing its surface area to
  the smallest possible size;
  meniscus
• Results from… water shows
  high surface tension
• Capillary action = attraction of
  a liquid to a solid; rises in a
  small tube against gravity
               Surface Tension
Look at the picture below. The milk forms small droplets that
     resemble a crown. But why does this happen?
 Because of the surface tension of water, which keeps the
                    droplets spherical.
                Do Now
1. What is the least common state of matter
   in the universe? Why?
2. What happens to liquids as you
   manipulate pressure and temperature?
   What liquid tends to “disobey” the KMT
   and normal behavior of liquids?
3. Why are ideal gases “ideal”?
Homework: SR on p. 348, 351, #35 on p.
   354 (LL)
                         Some terms:
        melting/freezing point             boiling/condensation point


         0ºC                                             100ºC
solid                            liquid                             gas
              MELTING                              BOILING




(ice)         FREEZING                           CONDENSING
                                 (water)                           (steam)
         More info on Liquids
• Vaporization – liquid
  to gas
• Evaporation – escape
  from a non-boiling
  liquid at its surface
• Boiling – vaporization
  through the entire
  liquid
• Freezing – physical
  change from liq.sol.
  through the loss of
  energy…
                          Solids
• Particles are tightly-
  packed d/t attractive
  forces  highly-ordered
• Motion is restricted, but
  present
• 2 types:
  1. crystalline = consists of
  crystals (orderly,
  geometric, repeating
  pattern)
  2. amorphous = particles
  are randomly arranged
           Properties of solids
•   Definite shape and volume
•   Definite melting point (d/t addition of heat)
•   High density and incompressible
•   Low rates of diffusion
                 Crystals
• Arranged in a lattice structure
• Smallest unit of a crystal that shows the 3-
  D pattern of the lattice = UNIT CELL
            Changes of State
• Phase = any part of a
  system that has a
  uniform composition
  and properties
• Condensation =
  process by which a
  gas turns into a liquid
• Vapor = a gas in
  contact with its liquid
  or solid phase
           Vapor Pressure
• The pressure exerted by a vapor that is in
  equilibrium with its corresponding liquid
• Develops in a closed system
• Increase AKE, increase particles leaving
  liquid, increased pressure
• Volatile liquids evaporate
  easily d/t weak IMF
            Notes on Boiling Point
• BP = when vapor pressure
  equals atmospheric pressure
• Increase pressure, increase
  BP = pressure cooker
• Molar Enthalpy of
  Vaporization = amount of
  heat needed to vaporize 1
  mole of a liquid at the liquid’s
  BP at a constant pressure; the
  stronger the attraction….
• Vapor pressure is directly
  proportional to temperature
• Vacuum evaporator – how
  does it work?
        Freezing and Melting
• Definitions?
• What is the difference b/t freezing water
  and ice? Boiling water and steam?
                Do Now
• Explain the importance and significance of
  this graph…
              More Vocab
• Molar heat of Fusion = the amount of
  heat required to melt one mole of a solid
  (symbol?)
• Sublimation vs. deposition
              Phase Diagrams
graph of pressure vs. temperature that shows the conditions
     under which the phases of a substance would exist
                     Water
• Most abundant liquid
  on Earth; essential to
  life; most reactions
  take place in it
  IMPORTANT!!!
• Review its structure
  and properties…
Water

								
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