molesetc Me
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http://www.quia.com/pages/hpedraza.html
 
OUTLINE:
Chapter 4: pages 121-135 Review Q's in the book are a good self test.

Go To Outline w/ hyperlink notes (good one w/ extra practice & notes!)

Avogadro's number: 6.023 E23

Mole: Avogadro's number of anything.
     A mole of marbles = 6.023 E23 marbles
     A mole of gummy bears = 6.023 E23 gummy bears

Molar Mass: (g/mol) Mass of one mole.  Equal to atomic weight but measured in grams. (Get from P.T.)

Molecular Weight: Sum of all atomic weights in a molecule.

Formula Weight: Same as Molecular Weight (but does not imply molecular (non-metal/non-metal) bonds.

    The Reason for The Mole Go To:2 Worlds of Chemistry
    You can practice w/ Mole Calculations good examples w/answers and practice!!!


molecules<------------->MOLES<-------------------->grams
              Av.# / 1 mole         molar mass (from P.T.)
              1mole / Av #          g/mole (or 1 mole/?g)

************************************************************
*write down what I give you
*look at what I am asking (look at units!)
*Use the proper conversion(s)
*Take it step by step!
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Molarity: Concentration in moles per liter.

     If I ask for concentration or molarity, get moles on top and liters on the bottom.  (start w/ what can get moles over one.  Once you have moles, divide by the volume.

     ALL OF THE REST OF THE TIME when doing molarity problems, USE the molarity as a conversion factor (moles<-->liters).

Percent Composition: (Part) DIVIDED BY (Whole) X 100%

     Get atomic masses from the P.T. (parts).  Add them up (don't forget to multiply by the subscripts) to get the whole.

Empirical Formula: The LOWEST whole number RATIO of elements in a compound.

***Convert to moles!!!***Use the P.T.
If you were given percents, assume 100g.  That way the masses are the same as the percents!

Molecular Formula: The actual ration in which elements hook up in a compound.

To determine Molecular formula, you need 3 things!
Empirical formulas
EFM-empirical formula mass
MM-molar mass (given in question)

Step #1 - MM/EFM = # (a magical whole number)
step #2 - multiply the subscripts of the empirical formula by the magic number

If you are not given the empirical formula, figure it out!
1>Get Moles of each element!!!!!
If I give you grams, great, use the PT to get the atomic mass of each.  24 g C 1 mole = 2 moles C
                       12g C
2>Write the wierd Eq (element symbols w/ moles as subscript)

3> Divide ALL subscripts by the smallest.
Multiply by 2,3,4 or 5 IF NEEDED.

Don't round until the very end!  Only round if it is .9something or .osomething.

ARE YOU READY FOR A TEST!?!?!?!?
Try links below for more notes and practice.  The practices have answer pages too.
My Quia activities and quizzes
Moles "The Beginning"
https://www.quia.com/cb/1824.html
in progress
Moles!!!!!: session moles
https://www.quia.com/quiz/599039.html
Will you just type in moles-PLEASE!
Too Many Moles!!!!
https://www.quia.com/cb/2102.html
for the test test test test...
Useful links
Last updated  2008/09/28 05:23:08 PDTHits  4237