A mole of a substance is a unique measurement of quantity used in chemistry.
12 = dozen 1 ream = 500 sheets

The mass in grams of 1 mole of a substance is called the molar mass
(g/mol) of the substance. (* The molar mass is numerically equal to the formula
Mass (amu).)

Converting between grams and moles
You can determine the number of moles by setting up an equation using a conversion factor which is a fraction whose value is equal to 1.
• If we are given the # of grams of a compound, you can determine the # of moles, & vise-versa.
• In order to convert from one to the other you must first calculate molar mass.

mol = g g/mol g = mol g/mol
“The Equation Triangle ” g mol g/mol

Example:
GRAMS  MOLES ( ÷)
A. The formula mass of sodium chloride
(NaCl) is 58 amu (23 amu + 35 amu). The molar mass of NaCl is then 58 g/mol. If one mole of NaCl has a mass of 58 grams, how many moles of NaCl are in 11.2 gram samples?

Example:
MOLES  GRAMS (x)
B. How many grams will you have in 2.50 moles of NaCl?

GRAMS  MOLES ( ÷)
2. 125 g of H
2
SO
4 =
? moles

MOLES  GRAMS (x)
7. 0.50 mol H
2
SO
4 =
? grams

Formula
HCl
H
2
SO
4
NaCl
Cu g/mol g
53.15
1.27
mol (n)
0.25
Equation g= g/mol x mol
3.55