5 Steps to a 5 AP Chemistry

CHAPTER

88 

Stoichiometry

IN THIS CHAPTER

Summary:The previous chapter on chemical reactions discussed reactants

and products in terms of individual atoms and molecules. But an industrial

chemist is not interested in the number of molecules being produced; she or

he is interested in kilograms or pounds or tons of products being formed per

hour or day. How many kilograms of reactants will it take? How many

kilograms of products will be formed? These are the questions of interest.

A production chemist is interested primarily in the macroscopic world, not the

microscopic one of atoms and molecules. Even a chemistry student working

in the laboratory will not be weighing out individual atoms and molecules,

but large numbers of them in grams. There must be a way to bridge the gap

between the microscopic world of individual atoms and molecules, and the

macroscopic world of grams and kilograms. There is—it is called the mole

concept, and it is one of the central concepts in the world of chemistry.

Keywords and Equations

Avogadro’s number =6.022× 1023 mol−1

Molarity, M=moles solute per liter solution

n=moles

m=mass

M=molar mass

n

m

M

=

7

KEY IDEA