1. The Mole
Chapter 10

2. Formula Mass:
Is what a single molecule “weighs” in amu’s (atomic mass units)
Revision:
So, 1 molecule of Water (H2O) weighs:
2 x 1.01 (for H) + 1 x (for O)
= amu’s

3. Example #2:
What is the mass of 1 molecule of Sugar(Sucrose)? (C6H12O6)
C: 6 x =
H: 12 x =
O: 6 x =
Do other examples?
a) CO2
b) (NH4)2CO3

4. 1 dozen = 1 baker’s dozen = 1 score = 1 gross = The Mole:
First, let’s look at names that reflect numbers:
1 dozen =
1 baker’s dozen =
1 score =
1 gross =

5. Let’s now focus on a particular isotope – Carbon-12
1 Carbon-12 atom weighs ______________
But this is an impractical measurement. We want to work in the mass unit of grams.
So, how many atoms of Carbon-12 would it take to weigh g.?

6. Amadeo Avogadro (Italian, 1776-1856) calculated the number to be 6
Amadeo Avogadro (Italian, ) calculated the number to be x 1023
and is also known as a
So now, the average atomic mass number also represents how many grams that element would weigh if you had 1 mole of that substance.

7. So, 1 mole of Water weighs:
H: 2 x g/mole = g/mole
O: 1 x g/mole = g/mole 
This # is known as the _____________(mass of 1 mole) of Water.
Examples. Calculate the Molar Mass of the following:
a.) SO2
b.) (NH4)3PO4

8. Mole to Mass & Mass to Mole Conversions
If we are given the # moles of a substance and we want to calculate how much it weighs (i.e. what’s its mass?), then we convert by using the _________________________!
E.g. What is the mass of 1.50 moles of Water?
1.50 mol. Of H2O x g of H2O = g of H2O
mol. of H2O
E.g.#2 What is the mass of 0.75 mol. Of Salt?

9. Now, going the other way.
How many moles are in 100.g of CO2 ?
100.g of CO2 x 1 mol. of CO2 = _______________
g of CO2
E.g.#2 How many moles are in a pound of Sugar?

10. Converting from moles to molecules & vicy versi
In these conversions, instead of using the _________________________, you use Avacado’s Avagadro’s Number. (NA)
Ex. How many molecules are in 1.50 moles of Water?
(remember: 1 mole = 6.02 x 1023 )
1.50 mol. x x 1023 molecules = ___________________
mol.
Ex.2) How many moles in x 1024 molecules of Salt?
2.107 x 1024 molecules x ____ = 3.50 moles
x 1023 molecules

11. Do these in-class egg samples:
1.) How many molecules are in 0.02 moles of Sugar?
2.) How many moles are in 3.01 x 1023 molecules of O2?
Let’s look at lots
of molecules
of Water.

12. Time to draw a MOLE diagram
I know what you’re thinking! Now we can do
Mass to Molecules conversions & vicy versi.
(Hint: it’s a 2 step Chain Method)
Ex. How many molecules are in 12.0g (~½ oz) of Water?
12.0g of H2O x _____________x________________________
mol of H2O
= 4.00 x 1023 molecules of H2O
Ex. What does 9.03 x 1022 molecules of Vitamin C weigh?
(Vitamin C = C6H8O6)

13. Standard Molar Volume
The Volume occupied by 1 mole of a gas is the Molar Volume.
The Volume occupied by 1 mole of a STP is known as the Standard Molar Volume of a gas and is equal to 22.4 L.
STP
V = 22.4 L/mol.  V = n x 22.4 L/mol. n
So 1 mole of any gas occupies STP, but their masses may be different.

14. So 2 moles of a gas will occupy twice the space (Volume) of 1 mole.
e.g. 2H O  H2O
(more examples: N2 + H2  NH3 ,…)
And remember:1 mole = 6.02 x 1023 molecules

16. (Diagram – New Mole Diagram)

17. Add that to the mole diagram…
Mass (Grams)
Mole
Molecules/ Atoms