Mole Relations

Samuel E. Hall, Jr.            Chgo H. S. for Ag. Sciences
                               3807 W. 111th Street
                               Chicago, Illinois 60655
                               312-881-5000

Objectives:

Grade level:  Sophomore chemistry

Students should be able to:  (a) define the "mole";  (b) state the mole 
relationship between components of a chemical equation. 

Apparatus Needed:

Per team of 3 students:
     30 Raisins
     40 Sunflower seeds (purchase a jar of the meat of sunflower seeds)
     30 M & M candy
     2-3 Napkins
     12 Sandwich bags
    
Transparencies and overhead projector or chalkboard.  Soap and towels for 
washing hands.   Set of "blackline" copies of transparencies will be sent upon 
request.  You can make the transparencies from these copies. 

Recommended Strategy:

Start by having the class form groups of three.  Tell the group that you need 
help in making some packages of trail mix.  Trail mix is a kind of nutrient mix 
used to munch on while hiking or bicycling and the like.  Our trail mix is 
skimpy for reasons of teaching the concept of "mole".

Give each team a recipe and an abundance of each of the three items  (raisins, 
sunflower seeds, and m & m's).  The group of students should count the 
ingredients and actually make the number of trail mix packages called for in the 
recipe.  

The students should count 1 dozen raisins, 3 dozen sunflower seeds, and 2 dozen 
m & m's.  With this stock, the group is instructed to make 1 dozen trail mix 
packages.  The actual number of each ingredient in each package of trail mix.  

PROJECT ON OVERHEAD:

1 dozen          3 dozen         2 dozen          1 dozen
raisins     +    sunflower   +   m & m's    +     trail mix
                 seeds                            packages

Continuing, groups should calculate that each of 12 trail mix packages contains 1 
raisin, 3 sunflower seeds and 2 m & m's. 


Next, ask students to calculate the number of ingredients necessary to make 1.5 
dozen trail mix packages.

Third step:  Ask students if you can abbreviate some names used in writing the 
recipe.  

PROJECT ON OVERHEAD:

2 dozen          3 dozen         2 dozen               1 dozen
  R        +        SS      +       MM       ------->     TM

Where R = raisin; SS = sunflower seed;  MM = m & m candy;  TM = trail mix 
package.

Ask the teams to determine the amount of each item to be placed in the trail mix 
packages.  It is important that answers be expressed in DOZENS not units.  In 
discussion attempt to have all teams understand how to calculate the number of 
dozen(s) of each ingredient needed.


PROJECT ON OVERHEAD:

3 R  +  3 SS  +  2 MM  ---->  1  TM 
  
Ask student if you can write a recipe without writing the word "dozen" because 
you are getting tired or writing "dozen" so many times.  After students are 
comfortable with the above relationships, introduce the term "mole".  The 
concept of dozen is similar to the concept of mole.  Define dozen and define 
mole.  Tell the students that one dozen of anything contains 12 items and one 
mole of anything contains 6 x 1023 items.  Now re-write the trail mix recipe 
substituting mole for dozen.  Write and discuss other examples of chemical 
equations to give practice in mole relationships.