Stoichiometry by the Recipe Method:  SBR

 

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SO2 info

 

All stoichiometry problems can be thought of as mole to mole problems.  This page shows how to apply the recipe method to a problem in which one is given the number of moles of one reaction component and is asked to solve for the number of moles of all of the other components. 

 

 

1.  USING MOLES OF THE GIVEN SUBSTANCE

2.  FIND THE MULTIPLIER FOR THE WHOLE EQUATION

3.  APPLY THE MULTIPLIER TO EVERY COMPONENT IN THE EQUATION CREATING AN EFFECTIVE EQUATION

This can best be shown by using a sample reaction. The standard equation is shown.   I have chosen the reaction that involves the burning of FeS2 in oxygen to form iron oxide and sulfur dioxide.  The importance of this reaction is further discussed by pressing here.

 

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

PROBLEM 1.  If you were given 12 moles of the FeS2  how many moles of each of the other components in this chemical recipe would be involved?

Obviously, the chemical recipe is being scaled up.  By How much?

USING THE IDEA OF THE MULTIPLIER FROM THE COOKIE ANALOGY 

   M~   = moles given / Moles from recipe (the coefficient)

OR     M~ =  12 moles FeS2 /4 moles FeS2 

   The multiplier is 3 in this case.  Every component in the standard equation recipe would be tripled and

3 *[4 FeS2 +  11 O2  ==>  2 Fe2O3    +  8 SO2]

the effective equation would be

12 FeS2  +   33 O2  ==>  6 Fe2O3    +   24 SO2

 

 note:  Chemists do not usually write of "standard" or of "effective" equations.  This is a construct of the author to distinguish between the common form of the equation and one in which the multiplier has been distributed over all of the coefficients.

  To see a more advanced problem click on next

 

Copyright (c) John Brodemus, 1995-2005.

brodemusj@sbcglobal.net

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This page was last updated: 02/27/04 04:00 PM