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The Mole

The Mole. What is a mole?. A conversion factor we use in chemistry to make it easier to talk about a very large amount of particles of elements or compounds 1 dozen bagels = 12 bagels 1 mole bagels = 6.02 x 10 23 bagels. Avogadro’s Number. Avogadro’s # = 6.02 x 10 23 units

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The Mole

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  1. The Mole

  2. What is a mole? • A conversion factor we use in chemistry to make it easier to talk about a very large amount of particles of elements or compounds • 1 dozen bagels = 12 bagels • 1 mole bagels = 6.02 x 1023 bagels

  3. Avogadro’s Number • Avogadro’s # = 6.02 x 1023 units • How does this number relate to a mole? • 1 mole = 6.02 x 1023 units *Units can be anything but in chemistry these units are referred to as: • Particles • Atoms • Molecules • Formula Units

  4. How big is 6.02 x 1023? • Astronomers estimate that there is a mole of stars in the Universe. • One mole of high school textbooks would cover the USA to a depth of about 300 Km. • One mole of marshmallows would cover the USA to a depth of 105 000 Km. • One mole of moles placed to head to tail would stretch 11 million light years and weigh 9/10 as much of the moon. • One mole of pennies would make at least seven stacks that would reach the moon. • One mole of watermelon seeds would be found inside a melon slightly larger than the moon.

  5. Examples • 1 mole Fe = 6.02 x 1023 atoms Fe • 1 mole C12H22O11 = 6.02 x 1023 molecules C12H22O11 • 1 mole Al = 6.02 x 1023 atoms Al • 1 mole BeF2 = 6.02 x 1023 formula units BeF2

  6. How is the mole measured in the lab? • It is impossible to count up individual particles of chemicals in the lab because of their small size • We must find another way to measure 6.02 x 1023 particles of a substance

  7. How does mass relate to the mole? • What does an amu (atomic mass unit) measure? 1 amu = 1.66053886 × 10-27 kilograms • A relative scale used to measure the mass of single elements or compounds

  8. Learning the termonology…Atomic Mass • Atomic Mass - measures the mass of a single atom in amu’s • Example: 1 atom Fe = 55.85 amu • *Always go to the hundredths place when taking measurements from the periodic table

  9. Formula Mass • Formula Mass - measures the mass of a single formula unit (ionic compound) in amu’s • Example: 1 formula unit BeF2 = 1Be 9.01 amu + 2F 2(19.00 amu) = 47.01 amu

  10. Molecular Mass • Molecular Mass - measures the mass of a singlemolecule in amu’s • Example: 1 molecule C12H22O11 = 12 C atoms 12(12.01 amu) + 22 H atoms 22(1.01 amu) + 11 O atoms 11(16.00 amu) = 342.34 amu

  11. Molar Mass • The mass of 1 mole of any substance in grams • Example: 1 atom Fe = 55.85 amu 1 mole (6.02 x 1023 atoms) Fe = 55.85 g 1 molecule C12H22O11 = 342.34 amu 1 mole (6.02 x 1023 molecules) C12H22O11 = 342.34 g

  12. What is a representative particle? • The smallest particle that represents the true identity of the entire substance without altering it’s characteristics or properties • Example: What is the representative particle of 52 Al atoms?

  13. Answer: 1 atom Al Example: What is the representative particle of 1 molecule of BeF2?

  14. Answer: 1 molecule BeF2 • 1 atom of Be or 1 atom of F would not truly represent the properties and characteristics of BeF2

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