5 Steps to a 5 AP Chemistry 2019

CHAPTER

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 chem-

ist 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 prod-

ucts 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 n

m

M

=

M = molar mass

7

KEY IDEA

(^88) ›