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How do mixtures differ from compounds

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					How do mixtures differ
 from compounds?
 Pure substances and Mixtures
       August 13th, 2007
              Phases of Matter
   Solid – definite shape and volume
   Liquid – indefinite shape but definite volume
   Gas – indefinite shape and volume
   Plasma – super-excited state of matter where
    electrons become delocalized
               Pure Substances…
   Have a uniform and definite composition
       Table salt in America is the same as table salt in UK
   Can be either an element or a compound
       What is the difference between elements and
        compounds?
   EX: H2O, NaCl, FeO, O2, Ag
                    Mixtures
   Combinations of two or more elements or
    compounds
   Usually does not involve chemical attraction
   Can be separated (more in a moment)
   Divided into two types
     Homogeneous-not uniform in composition
     Heterogeneous-uniform in composition
                  Mixtures (cont’d)
   How do we distinguish between the two?
       Can you tell if it is a mixture (and you know that it is)?
       If the answer is yes it is heterogeneous
       If the answer is no it is homogeneous
   Heterogeneous: fruit salad, macaroni and cheese,
   Homogeneous: sea water, blood, fruit punch, 14k gold
       If it is a liquid homogeneous mixture it is called a solution
   Can you come up with examples?
                  Mixtures (cont’d)
   Mixtures can be separated into their components
   Filtration – based on size
   Evaporation – based on phase change




   Distillation – based on differences in boiling points
                      Distillation
   Here are a couple of
    pictures of the distillation
    process
                How about this?
   Suppose you were
    working for a company
    that separated mixtures
    into their components.
    The company has
    recently purchased a
    dumpster full of a
    mixture of sawdust, salt,
    and iron filings. How
    would you propose the
    company separate this
    mixture?

				
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