Stoichiometry by the Recipe Method:  SBR

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    The recipe for making chocolate chip cookies had a list of ingredients and a product.  The recipe could be magnified to meet a demand for more product than the standard recipe could produce.  The standard recipe could also be reduced or shrunken down.  You want half the cookies, use half of each ingredient.  

    There are some limitations to this analogy.  Cookies are not exactly like chemical compounds.  There are many different types of chocolate chip cookies in the universe, and many different types can be made by making slight variations or substitutions in the recipe given.  For example, some cooks grind up some of their chocolate, leave the nuts out, use butter or applesauce for shortening substitutes.  Cookies are really mixtures.  The amount of each ingredient can be easily changed.  There are multiple recipes that will produce acceptable tasty results.   

    Compounds are said to have definite composition.  The formula tells how many of each atom make up the compound. Each ingredient has its formula written as an element or a compound.   Chemical compounds have a limited number of possibilities based on the oxidation states of the elements making up the compound.  

    Additionally,  take a look at the units for the cookie recipe.   There are cups, teaspoons, and tablespoons, not to mention eggs.  All of these units plus the possibility of pounds, ounces, pinches, and pints present a reader with a real predicament. 

    Chemists have different way to measure amounts (and also count atoms) for their recipes.  They use a unit called a mole. You may be given quantities of matter in solid, gas, or dissolved form.    Through various ways, these forms of matter can be converted into moles. You are asked to refer to your textbook and teacher for further information on how this idea came about. 

  If you need help on converting to moles click here

    In chemistry, the description of any reaction is written in the form of a balanced equation. 

    The neat thing about chemistry is that when you look at a balanced equation, you are really looking at a recipe. It is possible to look at the equation from two perspectives.

    At the microscopic or atomic level, the large numbers in front of each element or compound -known as coefficients- really tell you how many molecules there are of that substance in the reaction. 

    At the macroscopic level (that which we can see and measure directly) the coefficients- really tell you how many moles there are of that substance in the reaction. 

  To continue on with learning the new method of doing stoichiometry, press continue

Copyright (c) John Brodemus, 1995-2005.

brodemusj@sbcglobal.net

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This page was last updated: 03/03/04 04:31 PM