1. Measuring Quantities
How many donuts will we get if we ask for a dozen?
Twelve
How about a baker’s dozen?
Thirteen
So, we know “dozen” and “baker’s dozen” are both words that represent numbers

2. Measuring Quantities How many donuts will we get if we ask for a mole?
6.02 x 1023
Or, 602 with 21 zeros after it!
Since atoms are SO small we must count them in moles

3. The Mole
A.K.A. the Avogadro Constant, named in honor of Amadeo Avogadro
SI unit for amount of a substance
Abbreviation is mol
It is simply a WORD that represents a NUMBER

4. Converting Units 6.02 x 1023 particles = 1 mol
Equality that can be used as a conversion factor
Particles include atoms, molecules, etc.
Ex: How many atoms are in 5.0 moles of tin (Sn)?
5.0 𝑚𝑜𝑙 𝑆𝑛 1 × 6.02× 𝑎𝑡𝑜𝑚𝑠 𝑆𝑛 1 𝑚𝑜𝑙 𝑆𝑛
=3.0× 𝑎𝑡𝑜𝑚𝑠 𝑆𝑛

5. 4.52× 10 22 𝑚𝑜𝑙𝑒𝑐 𝐶 𝑂 2 1 × 1 𝑚𝑜𝑙 𝐶 𝑂 2 6.02× 10 23 𝑚𝑜𝑙𝑒𝑐 𝐶 𝑂 2
Converting Units
Ex: How many moles are in a sample of CO2 containing 4.52 x 1022 molecules?
1 𝑚𝑜𝑙𝑒 𝐶 𝑂 2 =6.02× 𝑚𝑜𝑙𝑒𝑐𝑢𝑙𝑒𝑠 𝐶 𝑂 2
4.52× 𝑚𝑜𝑙𝑒𝑐 𝐶 𝑂 2 1 × 1 𝑚𝑜𝑙 𝐶 𝑂 × 𝑚𝑜𝑙𝑒𝑐 𝐶 𝑂 2
= 4.52× × 𝑚𝑜𝑙 𝐶 𝑂 2
= 𝑚𝑜𝑙 𝐶 𝑂 2

6. Molar Mass 1 mole of NaCl formula units = 58.44 grams
1 mole of copper atoms = grams
1 mole of lead atoms = grams
Same number as formula mass
Measured in g/mol
Since molar masses are equalities, they can be used as conversion factors

7. Example Problem How many moles are in 78.54 g of KCl?
1 mole of KCl = ( ) g
1 mole of KCl = g
78.54 𝑔 𝐾𝐶𝑙 1 × 1 𝑚𝑜𝑙 𝐾𝐶𝑙 𝑔 𝐾𝐶𝑙 = 𝑚𝑜𝑙 𝐾𝐶𝑙
=1.053 𝑚𝑜𝑙 𝐾𝐶𝑙

8. Two-Step Problems
A 12.0-gram sample of iron (III) oxide, Fe2O3, contains how many formula units?
6.02 x 1023 formula units = 1 mole
1 mole of Fe2O3 = g (formula/molar mass)
12.0 𝑔 𝐹𝑒 2 𝑂 3 1 × 1 𝑚𝑜𝑙 𝐹𝑒 2 𝑂 𝑔 𝐹𝑒 2 𝑂 3 × 6.02× 𝑓𝑢𝑠 1 𝑚𝑜𝑙 𝐹𝑒 2 𝑂 3
= (12.0)(6.02× ) 𝑓𝑢𝑠=4.52× 𝑓𝑢𝑠

9. Summary Use Avogadro’s number to convert between moles and particles
1 mol = 6.02 x 1023 particles for every substance
Use molar mass to convert between moles and grams
1 mol = ___ grams
Grams depends on substance