South Pasadena • Chemistry
Name
Period
Date
2 · Elements and Compounds
2.4
Opening Problem
Suppose each bag of marbles contains 30 marbles, and
each bag of marbles weighs 38.1 grams.
Conversion Factors:
1 bag = 30 marbles
1 bag = 38.1 grams
(connects bunch with #)
(connects bunch with mass)
Bag Map
1 bag = 30 marbles
Marbles
1 bag = 38.1 g
Bag
Grams
NOTES
–
MOLES
How many marbles are in 2.8 bags?
30 marbles
2.8 bags  1 bag  = 84 marbles


How many marbles weigh 190.5 grams?
1 bag 30 marbles
190.5 g 38.1 g  1 bag  = 150 marbles



What is the mass of one marble?
1 bag
38.1 g
1 marble30 marbles  1 bag  = 1.26 g



1.26 g
This is the “marble mass”:
marble
What is a Mole?
Group words:
1 pair of socks = 2 socks
1 dozen eggs = 12 eggs
1 gross of goblins = 144 goblins
1 great gross of peanuts = 1728 peanuts
1 score of years = 20 years
1 great score of pennies = 400 pennies
1 mole of an item = 6.022 × 1023 items
A mole of grains of rice:
A mole of pennies:
A mole of grains of hockey pucks:
How much does a mole of marbles weigh?
6.022 × 1023 marbles  1.26 g 
1 mole 
1 mole

 1 marble
= 7.578 × 1023 g
Molar Mass
 Mass of one MOLE of an atom or compound in
g
grams. Units:
mol
mass of sample
 Formula: Molar Mass = moles of sample
Try it problem.
If 1 amu = 1.66 ×10−24 g, what is the mass of 1 mole of
carbon atoms in grams?
Mole  atoms  amu  grams
6.022 × 1023 atoms 12.01 amu 1.66 × 1024 g
1 mole

  1 atom   1 amu 
1 mol 
= 12.01 g
The value for the atomic mass is the mass of one atom
in amu as well as 1 mole of the atom in grams.
Atoms /
Molecules
Molar Mass
Moles
How many moles are in 56.9 g SF6?
1 mol SF6
56.9 g SF6 146.06 g SF  = 0.390 g SF6

6
How many SF6 molecules are in 3.7 moles?
6.022 × 1023 molecules SF6
3.7 mol SF6 
1 mol SF6


24
= 2.2 ×10 molecules SF6
What is the volume of 47.9 g SF6 (gas) at STP?
1 mol SF6
22.4 L SF6
47.9 g SF6 146.06 g SF   1 mol SF 

6 
6
= 7.35 L SF6
Mole Map
1 mole = 6.022 × 1023 atoms
Examples
What is the molar mass of SF6?
S: 1 × 32.06 = 32.06
F: 6 × 19.00 = 114.00
Molar Mass = 146.06 g/mol
Grams
For a gas at STP,
1 mol = 22.4 L
Liters
For fun …
 A mole of moles: http://what-if.xkcd.com/4/
 How big is a mole: http://ed.ted.com/lessons/daniel-dulek-how-big-is-a-mole-not-the-animal-the-other-one