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MIXTURES

VIEWS: 37 PAGES: 27

  • pg 1
									IMPURE SUBSTANCES:
     MIXTURES
 PROPERTIES OF MIXTURES
• A mixture is a combination of two or more
  substances that are not chemically
  combined
 PROPERTIES OF MIXTURES
• No Chemical Changes in a Mixture No
  chemical changes happen when a mixture
  is made. So, each substance has the
  same chemical makeup it had before the
  mixture was formed.
• Making a mixture is a
  physical change.
 PROPERTIES OF MIXTURES
• Separating Mixtures Through Physical
  Methods Mixtures can be separated by
  using physical changes. Physical changes
  do not change the identities of the
  substances.
• Some methods could be distillation,
  evaporation, filtration, dissolve, use of
  magnets, centrifugation,and
  chromatography.
    PROPERTIES OF MIXTURES
• The Ratio of Components
  in a Mixture The
  components of a mixture
  do not need to be mixed in
  a definite ratio.
• For example, granite is a
  mixture of different
  minerals. Different ratios of
  the minerals give granite
  different colors, but the
  mixture is always called
  granite.
  MIXTURES AND COMPOUNDS
      Mixtures                Compounds
Made of elements,         Made of elements
compounds or both
No change in original     Change the original
properties of the         properties of the
components                components
Heat or electricity not   Heat or electricity
required for separating   required for separating
the components            the components
Made using any ratio of   Made using a fixed ratio
the components            of components
      TYPES OF MIXTURES
• There are three types of mixtures:
Homogeneous mixtures                 Colloids
          Heterogeneous mixtures
 HETEROGENEOUS MIXTURES
• The different components can be seen as
  individual substances. We can almost
  separate the components with our eyes.
• The particles are visible (bigger particles)
 HOMOGENEOUS MIXTURES
• Have the same
  composition throughout.
• Any one region of the
  mixture has the same ratio
  of substance as any other
  region
• The components can´t be
  seen as individual
  indentifiable entities
• Mixed as much finer level,
  not readily distinguished
               COLLOIDS
• Is a mixture in which the
  particles are spread
  throughout but are not large
  enough to settle out

• The particles are not as
  small as those of a solution,
  however are smaller than
  those of a suspension
               COLLOIDS
• Particles in a colloid are large enough to
  scatter light. A colloid cannot be separated
  by passing it through a filter.
                COLLOIDS
• Consists of two separated
  phases: Disperse phase
  (or internal phase) and a
  continuos phase (or
  dispersion medium).
• May be solid, liquid or gas

• Some are translucent
  because of the Tyndall
  Effect (which is the
  scattering of light)
               Types of colloids
C                            Disperse phase
o
n             Gas            Liquid               Solid
ti
     Gas      None           Liquid aerosol Ex:   Solid aerosol
n                            fog, mist, hair      Ex: cloud,
u                            spray                smoke, air
o             Solid foam     Gel Ex: jelly,       Solid sol Ex:
s
     Solid
              Ex:aerogel,    silicagel            cranberry glass
p             styrofoam
h    Liquid   Foam Ex:       Emulsion Ex: milk, Sol Ex: blood
a             whipped        mayonnaise, hand
s             cream, shaving cream
              cream
e
TYPES OF HOMOGENEOUS
       MIXTURES
       SOLUTIONS (single phase)
       • A solution is a mixture that
         appears to be a single
         substance. The process in
         which particles of substances
         separate and spread evenly
         throughout a mixture is known
         as dissolving.
       • In a solution, the solute is the
         substance that is dissolved.
         The solvent is the substance
         in which the solute is
         dissolved.
    TYPES OF HOMOGENEOUS
           MIXTURES
• Examples of Solutions
  Liquid solutions include
  soft drinks, gasoline, and
  tap water. Solutions may
  also be gases, such as
  air.

• Solutions may also be
  solids, such as steel.
  Alloys are solid solutions
  of metals or nonmetals
  dissolved in metals.
               SOLUTIONS
• Particles in Solutions
  The particles in solutions
  are so small that they never
  settle out. They also cannot
  be removed by filtering.

• The particles in solutions
  are so small that they don’t
  even scatter light.
             SOLUTIONS
Concentrated or Dilute? Solutions can be
 described as being concentrated or dilute.
 But these two terms do not tell you the
 amount of solute that is dissolved.

     Concentration= amount of solute
                  amount of solution
• Solubility is the ability of a solute to
  dissolve in a solvent at a certain
  temperature. Depends on the attractions
  of solute particles for one another and
  attractions of solvent particles for one
  another.
• Dissolving Gases in Liquids Gases
  become less soluble in liquids as the
  temperature is raised.
• Dissolving Solids Faster in Liquids
  Three ways to make a solute dissolve
  faster are mixing the solution, heating the
  solution, and crushing the solute into
  smaller particles.
               SOLUTIONS
Unsaturated solution
  A solution that has not reached the limit of solute
  that will dissolve
Saturated solution
  A solution in which no more solute can be
  dissolved
  TYPES OF HETEROGENEOUS
         MIXTURES
• SUSPENSIONS
• A suspension is a mixture in
  which particles of a material are
  dispersed throughout a liquid or a
  gas but are large enough that they
  settle out.

• The particles in a suspension are
  large enough to scatter or block
  light. A suspension can be
  separated by passing it through a
  filter.
           SUSPENSIONS
• Different components are in different
  phase, such as solids in liquids or liquids
  in gases
• It is necessary to shake the substance
  before using it
 HETEROGENEOUS MIXTURES
• You can distinguish the two or more
  phases.
   SOLUTIONS, SUSPENSIONS
        AND COLLOIDS
  Solutions       Suspensions         Colloids

Uniformly         More or less     Intermediate
dispersed         dispersed        dispersed
Single phase      More phases      More phases

Small particles   Large particles Intermediate
                  that settle out  particles
Can´t scatter     Scatter or block Scatter light
light             light

								
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