The Mole

Stringer, S. C.                       Morgan Park High School
                                      881-5050
                          

Objectives:

Resolution of Problems:
   The role of a unifying hypothesis (law) and the reasoning 
   process leading to Avogadro's hypothesis.

Application of Hypothesis:
   Diatomic and monoatomic gaseous elements.  Avogadro's 
   hypothsis.  Determination of molecular weights, atomic 
   weights, etc.

Fundamental Skills:
   Solving problems by use of the gas constants:

          D(gas) = g mol wt(g)/22.4 l

          g mol wt(g) = D(gas) * 22.4 l

          D(gas) = (g/ml)*(1000ml/l)

Topic Statement:

The data below will apply to Avogadro's hypothesis.  This 
exercise preceded the review of the chapter on the gas laws:  
Boyle's, Charles', Gay-Lussac's, indicating similarities in the 
physical behavior of gases.  The question of whether gases 
display any similarities in chemical behavior may then be raised.  
Discussion of the experimental findings of Gay-Lussac and Proust 
leads to Gay-Lussac's Law.  Avogadro's hypothesis may then be 
used to explain Gay-Lussac's Law, and the inconsistency with 
Dalton's Theory may be resolved.  Also, consider the historical 
treatment and significance as in the basic chapter. 

The diagram of the mole concept and a work sheet follows below:

       divide by 22.4 l -->| M |--> multiply by GAW/GMW
volume (l) <---------------| O |----------------------> mass (grams)
     multiply by 22.4 l <--| L |<-- divide by GAW/GMW
                           | E |
  divide by 6.02 * 1023 -->|   |--> multiply by 6.02 * 1023
                             |
                             V
                          number of
                          particles

 Diatomic elements:              Define: 
         Br, I, N, Cl, H, O, F           Density = M/unit volume
                                         Volume = L * W * H
                                         Liquids = cylinder (3l)
     GAW = atoms                         Gas = displacement
     GMW = molecules                     Weight = grams
  D =  M/V
             /--- mass at 1 mole GAW/m wt.
MOLE -------<---- 6.02 * 1023 particles
             \--- at STP vol of 1 mole of gas = 22.4 l
 Substance                  Density             Volume of 1 mole
1.  Mercury               | 13.55 g/cm3    |
2.  Iron                  |  7.85 g/cm3    |
3.  Ethanol (C2H5OH)      |  0.80 g/ml     |
4.  Propanol (C3H8OH)     |  0.78 g/ml     |
5.  Carbon tetrachloride  |  1.59 g/ml     |

                 etc.

                            Chemistry
                    all of these contain 1 mole

SUBSTANCE    NUMBER OF MOLECULES  FORMULA  MASS(g)  ML ESTIMATE VOL.
Copper 8.92  |                   |        |        |   63.5/8.92 = 
Aluminum 2.70|                   |        |        |   27.0/27.0 = 10.0
Iron 7.86    |                   |        |        |   55.8/7.86 = 
Lead 11.34   |                   |        |        |
Zinc 7.14    |                   |        |        |
Tin 5.75     |                   |        |        |
       etc.  |                   |        |        |