EMPIRICAL FORMULAS

Arzie R. Thomas                G. W. Carver Area High School
                               13100 South Doty Road
                               Chicago, IL 60627
                               1-312-821-2650 

Objective:
      Upon the completion of this lesson when asked 95% of the students will 
orally, on written test or demonstrate how to find an empirical formula. 
                                                                        
      Find the molecular formula, given the molecular mass and the empirical 
formula. 

Materials:
      Squares of paper with symbols and charges; squares of paper with carbon and 
it's electron dots and hydrogen and it's electron dots. 

Strategies:
 1.  Define empirical formula.
 2.  Pass out ions and have students form formulas.     
 3.  Have students give you  formulas; you place the formulas on the
     board.
 4.  Go through the formulas and point out the correct formulas, indicate   
     why they are correct, and go through the wrong ones and correct them.   
     Tell students that these are ionic formulas and they are always written
     in their empirical formula.
 5.  Pass out ions of carbon with its electron dots and hydrogen with its     
     electron dots.  Explain that the organic compounds are not like the
     inorganic compounds, some of them have two formulas.
 6.  Have the students make formulas of some of the alkanes.
 7.  Get the formulas and place them on the board.
 8.  Go through each formula for correctness and get the empirical formulas.
 9.  After the students are sure that they fully understand empirical 
     formulas, assign them problems to find the empirical formulas.
10.  Give the student the molecular mass for their empirical formula and
     show them how to find the molecular formula.
ll.  After the student are sure that they understand assign them problems.