
 Conversions
 Mass  Mole  Numbers

Avogadro's number, the mole concept, formul weights and molar
mass allow us to convert among masses, moles and number of atoms
or molecules. For example suppose we have 25 g of acetic acid
(C2H4O2). The molar mass of acetic acid is 60 g/mol. we can ask
the following questions for 25 g of acetic acid:
We can answer these questions in the following way:
How
many moles of acetic acid? 
= 25 g x (1 mol acetic acid/60 g) = 0.417 mol 
How
many moles of carbon? 
=
2x0.417 mol = 0.834 mol of C 
How many moles of hydrogen? 
= 4x0.417 mol = 1.67
mol of H 
How many moles of oxygen? 
= 2x0.417 mol = 0.834
mol of O 
How many total moles of atoms? 
= 8x0.417 mol = 3.34
mol of atoms 
How many carbon atoms? 
= 0.834 mol x(6.022x10^+23/mol) = 5.02x10^+23 C atoms 
How many hydrogen atoms? 
= 1.67 mol x(6.022x10^+23/mol) = 1.01x10^+24 C atoms 
How many oxygen atoms ? 
= 0.834 mol x(6.022x10^+23/mol) = 5.02x10^+23 O atoms 
How many total atoms? 
= 3.34 mol x(6.022x10^+23/mol) = 2.01x10^+24 total atoms 
Alternatively, we could have started with a number of molecules,
and then convert this number to number of C atoms, mass of C
atoms, moles of C atoms, total moles etc.. The procedure for
this calculation is similar to that above..
