1. Chemical Stoichiometry: The Mole Concept
Mr. Forte
Atascadero High School

2. Mole Concept
A mole is a word that represents a number, much like a dozen.
One mole = 6.02 x of anything. Known as Avogadro’s Number.
The average atomic mass of any element expressed in grams provides exactly one mole of atoms of that element!

3. >, <, or = to, One Mole?
17.0 grams of Neon (Z=10)
45.5 grams of Sodium (Z=11)
>
158 grams of Radon (Z=86)
<
grams of Iron (Z=26) =
8.7 grams of Lithium (Z=3)
>

4. Which Contains More Atoms?
>
25 g of Nickel (Z=28)
25 g of Copper (Z=29)
<
25 g of Zinc (Z=30)
25 g of Carbon (Z=6)
>
8 g of Helium (Z=2)
400 g of Lead (Z=82)

5. Molar Mass
The mass in grams of any element or compound that provides exactly one mole of units of that substance is called its molar mass.
The molar mass of iron (Fe) is 55.8 grams
The molar mass of carbon dioxide, CO is 44.0 grams

6. Conversions
The molar mass of a substance is used to convert between mass (grams) and moles (number of particles).
Avogadro’s Number is used to convert moles or grams into an actual number of particles. It can be set equal to one mole or the molar mass of any substance.

7. What mass of carbon (C) is found in a 3.45 mol sample?
Molar mass of carbon = 12.0 g/mol
3.45 mol (12.0 g C) = 41.4 g
(1 mol C)

8. How many moles of fluorine (F) atoms are found in a 100. g sample?
Molar mass of fluorine = 19.0 g/mol
100. g F (1 mol F) = 5.26 mol F atoms
(19.0 g F)

9. How many actual atoms of zinc (Zn) are found in a 7. 50 gram sample
How many actual atoms of zinc (Zn) are found in a 7.50 gram sample? (Zn = 65.4 g/mol)
65.4 g Zn = 6.02 x 1023 atoms of Zn
7.50 g Zn (6.02 x 1023 atoms of Zn) =
(65.4 g Zn)
6.90 x 1022 atoms of Zn

10. How many actual atoms of tin (Sn) are found in a 3
How many actual atoms of tin (Sn) are found in a 3.25 moles sample of tin?
(1 mole Sn = 6.02 x 1023 atoms of Sn)
3.25 mol Sn (6.02 x 1023 atoms of Sn) =
(1 mol Sn)
1.96 x 1024 atoms of Sn