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Conversions _Dimensional Analysis_

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Conversions _Dimensional Analysis_ Powered By Docstoc
					Grams→Particles
Grams→Particles
       How many formula units are there in 24 grams of FeF3?




24 g FeF3

  Start with
 the known
   quantity
Grams→Particles
           How many formula units are there in 24 grams of FeF3?




24 g FeF3 x
                          g FeF3

                      Starting unit
  Start with
                       must be in
 the known
                           the
   quantity
                      denominator
                       to cancel it
                           out
 Grams→Particles
              How many formula units are there in 24 grams of FeF3?



             1 mol FeF3
24 g FeF3 x
            112.8 g FeF3

 Start with
the known        112.8 g FeF3 is equal to 1 mol FeF3
  quantity          (it’s the molar mass of FeF3)
 Grams→Particles
      How many formula units are there in 24 grams of FeF3?



             1 mol FeF3
24 g FeF3 x
            112.8 g FeF3

      the units of “g FeF3”
           cancel out
Grams→Particles
      How many formula units are there in 24 grams of FeF3?



             1 mol FeF3
24 g FeF3 x              x
            112.8 g FeF3   mol FeF3


                         mol FeF3 is not desired, so it
                         must be in the denominator to
                                 cancel it out
 Grams→Particles
      How many formula units are there in 24 grams of FeF3?



             1 mol FeF3
24 g FeF3 x              x
            112.8 g FeF3   mol FeF3

                             the units of “mol FeF3”
                                   cancel out
Grams→Particles
        How many formula units are there in 24 grams of FeF3?


                                                 23
            1mol FeF 3     6.02 x 10 f.u. FeF3
24 g FeF x
        3                x
           112.8 g FeF 3       1mol FeF 3



                      6.02 x 1023 f.u. FeF3 are equal to 1 mol FeF3
  Grams→Particles
            How many formula units are there in 24 grams of FeF3?



            1mol FeF       6.02 x 1023 f.u. FeF
24 g FeF x
        3
                     3
                         x                     3
                                                  1.28 x 1023 f.u. FeF3
           112.8 g FeF 3       1mol FeF   3




                 24 x 1 x (6.02 x 10 23 )
                                           1.28 x 10 23

                       112.8 x 1
  Grams→Particles


            1mol FeF       6.02 x 1023 f.u. FeF
24 g FeF x
        3
                     3
                         x                     3
                                                  1.28 x 1023 f.u. FeF3
           112.8 g FeF 3       1mol FeF   3




            Another way to write this…


24 g FeF     1mol FeF       6.02 x 1023 f.u. FeF
        3            3                          3
                                                     1.28 x 1023 f.u. FeF3
            112.8 g FeF3        1mol FeF   3
 Grams→Particles



    It’s called a “fence post” method or “t-chart” by some. In
    place of an “x” sign, vertical lines are used to separate
    parts of the calculation


24 g FeF     1mol FeF      6.02 x 1023 f.u. FeF
        3            3                         3
                                                    1.28 x 1023 f.u. FeF3
            112.8 g FeF3       1mol FeF   3

				
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posted:1/23/2013
language:English
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