The Mole

The mole is the most fundamental measurement quantity in chemistry.  When you are trying to solve problems and don't know what to do, try to convert whatever you have into moles, it is almost always the best place to start.  I call moles the "super secret unit of chemistry" because you need to understand and be able to use the concept of moles to do chemistry calculations.  It is fundamental to further study in chemistry.  It is the first "secret" of being able to do chemistry.

The mole is how we count in chemistry.  One mole is equal to 6.02x1023 particles.   It is no different in concept than a dozen which most people know is 12 or a ream (usually in reference to paper) being equal to 500.  It is simply a convienient way to measure in chemistry because one mole of atoms is equal to the average atomic mass of that element in grams.  This is the definition of molar mass, molecular mass or formula mass.  With this idea we are able to measure the mass of a compound and "count" how many atoms are present.  The "representative particles" that we use most often with a mole are atoms (representative particles of elements), formula units (representative particles of ionic compounds) and molecules (representative particles of covalent compounds).


Unit VI  Chemical Quantities

Be able to solve problems using scientific notation and dimensional analysis (the factor-label method).
Be able to solve problems using the concepts of a mole, molar mass and Avogadro’s number.
Be able to solve problems using molarity and percents.
Be able to calculate percent composition of compounds.
Be able to calculate Empirical and Molecular Formulas.
Be able to determine the percent of water in a hydrate.

Terms:  molecular mass, formula mass, molar mass, mole, Avogadro constant, molarity, percent composition, hydrate
Important people of history:  Avogadro

Suggested Problems:  Read Chapter 7 and Chapter 13, Section 2
   pg 233 (1-13) pg 240 (8-12) pg 248 (4-8) pgs 251-256 (1-3, 14, 16-18, 22-58, 62-84) pg 467 (2-12) pgs 488-492 (47-61)





Return to the HHS Science Home Page

Links

History of the mole
Calculations Practice
National Mole Day Org