1. The Mole This is a quantity of atoms or molecules. A Dozen = 12 A Gross = 144 It allows us to “count” how many atoms we are using in a reaction!

2. The Mole In chemistry the mole = …. 602,000,000,000,000,000,000,000 atoms or molecules. 6.02x10 23 atoms or molecules. This number is called Avogadro’s Number.

3. The Mole How big is a mole? (useless facts ahead!) A mole of watermelon seeds would be found in a watermelon that is slightly larger than the moon. A mole of M&M’s would fill one- third of the Earth’s oceans.

4. The Mole A mole of donut holes could cover the Earth 5 miles deep. A mole of red blood cells would exceed the number found on every human on earth combined. A mole of pennies could pay the US national debt roughly 500 million times. (approx. $12 trillion as of today)

5. How Can We Count Atoms? Avogadro’s Principle Equal volumes of gases (same Temperature & Pressure) have equal numbers of molecules. [http://www.bulldog.u-net.com/avogadro/imgs/avogad.gif]

6. Early 1900’s – Scientists find approximate size of an atom. The mole is then defined as the number of atoms in 12.0 g of carbon. (Avogadro’s Number!!!) How Can We Count Atoms?

7. The Mole II (Return of Bridges) Mole (mol) – The number of atoms that are found in the molar mass of a given element. Molar mass (M) is the atomic mass of an element measured in grams. [http://www.userwebs.pomona.edu/~cjt04747/Chem1/color_mole.jpg]

8. The Mole II (Return of Bridges) 6.02 x 10 23 In 12.0 g of carbon Atoms In 18.0 g of H 2 O Molecules (covalent!) In 58.5 g of NaCl Formula Units (Ionic!) Conversion factors for mole problems

9. The Mole II (Return of Bridges) Example: How many molecules of O 2 are there in 1.50 moles of O 2 ? 1.50 mol O 2 6.02 x 10 23 molec. 1.0 mol O 2 = 9.03 x 10 23 molecules O 2 Watch Significant Digits!!!

10. The Mole II (Return of Bridges) Example: How many grams of C 2 H 4 are there in 3.0 moles of C 2 H 4 ? 3.0 mol C 2 H 4 28.0 g C 2 H 4 1.0 mol C 2 H 4 = 84 g C 2 H 4

11. The Mole II (Return of Bridges) Example: How many grams of Ca are there in 7.2 x 10 22 atoms of Ca? 7.2 x 10 22 atoms40.1 g Ca = 4.8 g Ca 6.02 x 10 23 atoms