Chemistry 20 – Unit Two

Section 6 Notes:

-  Introduction to the Mole

1. Mule Lab

2. Mole: A large number used by chemists to count atoms of molecules

-  6.02 x 1023 (Avogadro’s Number)

Note: mole is a number like a dozen or a million, but a large number. We are not going to use the actual number often.

6.02 X 1023 Watermelon Seeds: Would be found inside a melon slightly larger than the moon.

6.02 X 1023 Donut Holes: Would cover the earth and be 5 miles (8 km) deep.

6.02 X 1023 Pennies: Would make at least 7 stacks that would reach the moon.

6.02 X 1023 Grains of Sand: Would be more than all of the sand on Miami Beach.

6.02 X 1023 Blood Cells: Would be more than the total number of blood cells found in every human on earth.

6.02 X 1023 C02 Molecules: Would be found in 1 Mole BalloonTM at STP.

1 Liter bottle of Water contains 55.5 moles H20

5 Pound Bag of Sugar contains 6.6 moles Of C12H22O11

1 Mole BalloonTM: Contains 22.4 Liters of any gas at STP.

There are 3 types of moles that live underground in North America: Eastern Mole, Hairy-Tailed Mole and Star-Nosed Mole

Molar Mass:

-  The mass of one mole of atoms (or molecules)

Element / Atomic Mass / Molar Mass
Cu / 63.5 / 63.5 g/mol
Fe / 55.8 / 55.8 g/mol
Al / 27.0 / 27.0 g/mol
S / 32.1 / 32.1 g/mol
O / 16.0 / 16.0 g/mol

Conversions

Number ß à Moles ß à Mass

Note: Moles = mass / molar mass

n = m/mm

Examples:

1.  Convert 12.04 x 109 atoms to moles:

12.04 x 109 x 1 mole/6.02 x 1023 atoms = 2.00 x 10-14 moles

2.  Convert 2.51 moles of pennies to pennies

2.51  moles of pennies x 6.02 x 1023 pennies/1 mole of pennies = 1.51 x 1024 pennies.

3.  Change 3.42 moles of carbon to grams

3.42 moles of carbon x 12.0g/1mole of Carbon = 41.0g

4.  Change 109.5g of Sulfur to moles

109.5g of Sulfur x 1 mole/ 32.1g of Sulfur = 3.41 moles

5.  Change 27.09 x 1023 atoms of Lithium to grams

27.09 x 1023 atoms of Lithium x 1 mole/ 6.02 x 1023 atoms of Li = 4.50 moles of Li

4.50 mole x 6.02x1023 g/ 1 mole = 2.71 x 1024 g

Practice questions – converting mass to moles to atoms

Counting Atoms Assignment