1. Weighing Carbon Can’t weigh individual atoms
Define in terms of grams, not amu
Reference: 12 g of carbon-12
Contains 6.02 x 1023 carbon atoms
Avogadro’s Number
= 1 mole

2. The McDondald’s Corporation: “Billions Served Daily”
How big is a mole?
The McDondald’s Corporation:
“Billions Served Daily”
How long to serve a mole?
6.022 x 1023 hamburgers
3.6 x 109 hamb/day
= 1.67 x 1014 days
= 458 billion years!

3. One Mole of: S C Hg Cu Fe

4. C 6
Atomic #
Symbol
Name
Carbon
MOLAR
Mass (in g)
12.01

5. Molar mass is the mass of 1 mole of in grams marbles atoms
eggs
shoes
Molar mass is the mass of 1 mole of in grams
marbles
atoms
1 mole 12C atoms = x C = g
1 12C atom = amu
1 mole C atoms = g
1 mole lithium atoms = g of Li
For any element
atomic mass (amu) = molar mass (grams)

6. Do You Understand Molar Mass?
How many atoms are in g of potassium (K) ?
1 mol K = g K
1 mol K = x 1023 atoms K
1 mol K
39.10 g K x x
6.022 x 1023 atoms K
1 mol K =
0.551 g K
8.49 x 1021 atoms K

7. molecular mass (amu) = molar mass (grams)
Molecular mass (or molecular weight) is the sum of
the atomic masses (in amu) in a molecule.
SO2 1S
32.07 amu 2O
+ 2 x amu
SO2
64.07 amu
For any molecule
molecular mass (amu) = molar mass (grams)
1 molecule SO2 = amu
1 mole SO2 = g SO2

8. Do You Understand Molecular Mass?
How many moles of C3H8O are in 72.5 g?
1 mol C3H8O = (3 x 12) + (8 x 1) + 16 = 60 g C3H8O
1 mol C3H8O
60 g C3H8O x
72.5 g C3H8O
= 1.2 moles C3H8O

9. Do You Understand Molecular Mass?
How many H atoms are in 72.5 g of C3H8O ?
1 mol C3H8O = (3 x 12) + (8 x 1) + 16 = 60 g C3H8O
1 mol C3H8O molecules = 8 mol H atoms
1 mol H = x 1023 atoms H
1 mol C3H8O
60 g C3H8O x
8 mol H atoms
1 mol C3H8O x
6.022 x 1023 H atoms
1 mol H atoms x =
72.5 g C3H8O
5.82 x 1024 atoms H

10. Chemical Calculations
1 mole of CO2 = 6.02x1023 molecules CO2
Has a molar mass (M) of
= g

11. So 1 mol of carbon weighs 12.01 g
1 mol of CO2 weighs g
12.01g C .
44.01g CO2
x 100% = 27.3%
If 3.3 Gt of C are put in the air:
3.3 Gt C x Gt CO2 = 12 Gt CO2 put in the air
12.01 Gt C

12. Section 3.7 Chemical Reaction: Substances  new substances
Chemical Equation: Symbols showing what
happens

13. Physical states: sometimes omitted
2 Mg(s) + O2(g) MgO(s)
(Reactants)
(Products)
Physical states: sometimes omitted
MUST be balanced!