Stoichiometry by the Recipe Method:  SBR

 

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shortcut method

 

    The following equation is used throughout this tutorial.  Here it is used to demonstrate the traditional method of doing stoichiometry in what is called a mole to mole problem.  

4 FeS2  +   11 O2  ==>  2 Fe2O3   +  8 SO2

Problem:  How many moles of each component in the equation would be needed (or made) if you are given 12 moles of the FeS2.

  The traditional approach to solving this problem involves starting with the amount of a substance given in the problem and then multiplying by a mole ratio. The coefficients of the given and unknown components are used to make the ratio.   As is common factor label practice, the numerator contains the units you are going to, and the denominator the units you are leaving.

Doing the same problem using the traditional approach, you will need to make three mole ratios to solve this problem.

A.

12 moles FeS2  * 11 moles O2
                                 ------------------                           =     33 moles O2
                             4 moles FeS2  

B.

12 moles FeS2  * 2 moles Fe2O3 
                                 -------------------                          =   6 moles Fe2O3
                           4 moles FeS2     

C.CC. 

12 moles FeS2 *   8 mol SO2    
                           -----------                        =   24 moles SO2     
                            4 mol FeS2

Why do three calculations each with a different mole ratio when a shortcut is available that will simplify the work.

    

  

  

 

Copyright (c) John Brodemus, 1995-2005.

brodemusj@sbcglobal.net

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This page was last updated: 02/28/05 11:14 PM