1. Chapter 10 - The Mole & Avogadro’s Number
Measuring Matter
Sections 10.1  10.3

2. Measuring Matter/Counting Units
One pair = 2
(boots, shoes)
One dozen = 12 (eggs, donuts, roses)
One gross = 144 (pencils)
One ream = 500 (sheets of paper)

3. Measuring a Mole – units used to count particles
Atoms are so tiny chemists count them using a unit of measurement called a “mole”
1 mole = 6.02 x 1023 (Avogadro’s Number) atoms/particles/ions/formula units/molecules
This is a very large number because it measures extremely tiny items
602,000,000,000,000,000,000,000

4. How Big is a Mole?
One mole of pennies would allow every person on Earth to spend a million dollars an hour, day and night, and still have half of it unspent when they died
One mole of popcorn would cover every dry
surface of the Earth to a depth of six miles
One mole of stacked pennies would reach to the moon and back 16 times
One mole of marshmallows
would cover the United States
to a depth of 650 miles

5. History of Avogadro’s Number
Avogadro: 1811 – equal volumes of gases at the same temperature and pressure contain equal numbers of molecules
Cannizzaro: 1861 – developed atomic weights for known elements
Loschmidt: 1865 – determined the number of atoms present in a given volume of air
Ostwald: 1902 – developed the concept of the mole
1971 – the true value, 6.02x1023, was actually determined and is called Avogadro’s number since the entire string of events started with his findings in 1811

6. The Law of Conservation of Mass
According to the Law of Conservation of Mass,
Mass of reactants = mass of products
Mass of starting substances = mass of ending substances
So the production of one water molecule requires 2 hydrogen atoms and 1 oxygen atom.
Therefore:
two atoms of hydrogen + one atom of oxygen  1 water molecule
And
12.04x1023 hydrogen atoms x1023 oxygen atoms 
6.02x1023 water molecules

7. The Law of Definite Proportions and Ratios of Atoms
Law of Definite Proportions – atoms combine in small whole number ratios to form compounds
Example: Water- two atoms of Hydrogen will always combine with one atom of Oxygen to form one molecule of water

8. Relationships between moles, atoms and the gram mole
The atomic mass ratio of hydrogen to oxygen is 1 amu : 16 amu
The gram mole ratio between hydrogen and oxygen is 1 g : 16 g
So, chemists can determine how many atoms are present in a sample.
One gram of hydrogen would contain exactly 6.02x1023 atoms, or Avogadro’s Number of atoms. Two grams of hydrogen atoms would contain 12.04x1023 hydrogen atoms.
Also, 16 gram moles of oxygen would contain 6.02x1023 atoms.
Therefore: 1 gram of hydrogen = 6.02x1023 atoms = 1 mole
2 grams of hydrogen = 12.04x1023 atoms = 2 moles
16 grams of oxygen = 6.02x1023 atoms = 1 mole
32 grams of oxygen = 12.04x1023 atoms = 2 moles

9. In Conclusion:
2 atoms of hydrogen + 1 atom of oxygen = 1 water molecule
2 amu of hydrogen amu’s of oxygen = 18 amu’s of water molecules
2 g of hydrogen grams of oxygen = 18 grams of water molecules
12.04x1023 atoms H x1023 atoms O = 6.02x1023 atoms H2O molecules
2 moles of H atoms mole of O atoms = 1 mole of water molecules

10. Moles Particles Conversion
Atoms, molecules, ions, formula units
x 6.02 x 1023
÷ 6.02 x 1023
Moles

11. Example Problems: Convert 3.5 moles to atoms
Convert x 1023 atoms to moles

12. Convert from moles to particles
3) 2.7 moles of lithium
4) 1.8 moles of sodium chloride
5) 5.3 moles of bromine
6) 4.7 moles of potassium oxide

13. Convert from particles to moles
7) 4.32 x 1024 atoms of calcium
8) 2.7 x 1020 atoms of copper
9) 2.5 x 1024 molecules of sodium chloride
10) 5.32 x 1023 molecules of calcium chloride

14. You try these… 11) 25 moles to particles
12) 4.08 x 104 particles to moles
13) moles to particles
14) 2.3 x 1016 particles

15. Homework Complete on another sheet of paper showing your work!
Moles to particles
1) 2.7 moles
2) 1.8 moles
3) 5.3 moles
4) 4.7 moles
Particles to moles 5) 4.32 X 1024
6) 2.70 X ) 2.50 X ) 5.32 X 1023