1. THE MOLE
Not these kinds of moles, but…

2. The Science Mole
The “mole” is just a number, the same way a “dozen” is 12 of something….
A dozen eggs = 12 eggs
A dozen people = 12 people but 2 dozen (24) legs

3. The mole is much MUCH larger than a dozen.
1 mole = 6.02 X 1023

4. n (mole) = _________________
THE MOLE (n)
A Mole is the amount of substance that contains 6.02 x (Avogadro’s #) particles of that substance
The mass of a mole of any element or compound is called its molar mass.
n (mole) = _________________
mass of a substance (g)
molar mass of substance (g/mol)

5. MOLAR MASS Examples: TO FIND MOLAR MASS OF SUBSTANCE
add up the molar masses
of the elements shown
in the formula
Examples:
1. H2O (water)
Hydrogen = 1.0g/mol x 2
Oxygen = g/mol x 1
Molar Mass = 18 g/mol
2. KNO3 (potassium nitrate)
Potassium (K)= 39.1g/mol x 1
Nitrogen (N) = 14 g/mol x 1
Oxygen (O) = 16g/mol x 3
Molar mass = g/mol
THEREFORE: 1 mole of water has a molar mass of 18g/mol and 1 mole of potassium nitrate has a molar mass of 101.1g/mol.

6. EX EX What is the molar mass of NaCl? 58.5 g/mol
Na = 1 x 23g/mol = 23
Cl = 1 x 35.5 g/mol = 35.5
58.5 g/mol EX
What is the molar mass of (NH4)2SO4
N = 2 x 14 g/mol = 28
H = 8 x 1 g/mol = 8
S = 1 x 32 g/mol = 32
O = 4 x 16 g/mol = 64
132 g/mol

7. n (mole) = _________________
RECALL
n (mole) = _________________
mass of a substance (g)
molar mass of substance (g/mol)
moles
grams
convert

8. EXAMPLE # 1
How many moles of hydrochloric acid are in 100 grams of hydrochloric acid (HCl)?
n (# of moles)= grams
molar mass
n = ?
g = 100
Molar Mass = 36.5g/mol
n = 100 g
n = 2.74 mol
36.5g/mol
Hydrogen 1g/mol x 1
Chlorine g/mol x 1
molar mass = 36.5 g/mol
HCl

9. EXAMPLE # 2 How many grams are in 11.1 moles of water (H20)?
n (# of moles)= grams
molar mass
n = 11.1 moles
g =
Molar Mass = 18 g/mol
11.1 moles = _____ g/mol
g = 200 grams
Hydrogen g/mol x 2
Oxygen g/mol x 1
molar mass = 18 g/mol

10. EXAMPLE # 3
What is the mass of 0.42 moles of potassium nitrate (KNO3)?
n(moles) = moles
Molar Mass = g/mole
g = ?
n (# of moles)= grams
molar mass
0.42 mole = __g__
101.1 g/mole
K = g/mole
N = g/mole
0 = 16 g/mole
X 3 = 48g/mole
101.1 g/mole
g = grams

11. KEY POINTS EXAMPLE Hydrogen = 1.0g/mol x 2
The mass of a mole of any element or compound is called its molar mass.
A Mole is the amount of substance that contains
6.02 x (Avogadro’s #) particles of that substance
Formula to convert between moles and mass (g) is:
EXAMPLE
1. H2O (water)
Hydrogen = 1.0g/mol x 2
Oxygen = g/mol x 1
Molar Mass = 18 g/mol
n (# of moles)= grams
molar mass

12. PRACTICE PROBLEMS Study guide, Module 3, page 11 and 18
436 WORKSHEET # 2