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The Mole

The Mole. So far we have been dealing with number on the atomic scale…. Atomic number = # of protons Mass number = # protons + # of neutrons Atomic mass = # of amu in one average atom. So far we have been dealing with number on the atomic scale….

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The Mole

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  1. The Mole

  2. So far we have been dealing with number on the atomic scale… • Atomic number = # of protons • Mass number = # protons + # of neutrons • Atomic mass = # of amu in one average atom

  3. So far we have been dealing with number on the atomic scale… • Rather than always working on the atomic scale, chemists often find it useful to work with a unit that represents a large collection of atoms. • Such a unit serves as a bridge between the invisible world of atoms and the macroscopic world of materials and objects.

  4. We need…. • The MOLE! • Abbreviation = mol • The mole is a unit of measure – a unit of “how many”. • 1 mole = 6.02 x 1023 particles • 6.02 x 1023 is called Avagadro’s number, in honor of AmedeoAvagadro’s contributions to chemistry.

  5. The Mole: • What is so special about this number? • The answer is that there is exactly 1 mole of atoms in the atomic mass of an element when that mass is expressed in grams. • For example: • What is the atomic mass of C-12? • Atomic mass = 12 amu, expressed in grams  12g • In exactly 12 g of C-12, there is one mole of atoms (6.02 x 1023).

  6. The Mole: • So, in exactly 12.01 g of natural carbon there are 6.02 x 1023 atoms. • And, 6.02 x 1023 atoms = 1 mole. So 1 mole of carbon = 12.01 g • Hmm….those sound suspiciously like conversion factors…….

  7. Lets Practice!

  8. How many atoms are in 1.00 mole of gold? • What do we want? • Atoms of Au • What do we know? • 1.00 mole Au • 6.02 x 1023 atoms 6.02 x 1023 atoms 6.02 x 1023 Atoms Au 1.00 mole Au = 1 mole

  9. How many molecules are in 2.00 moles of water? • What do we want? • Moles of water • What do we know? • 2.00 moles of water • 6.02 x 1023 atoms 6.02 x 1023 molecules 1.20 x 1024 Molecules H2O 2.00 mole H2O = 1 mole

  10. How many marbles are in 1.00 mole of marbles? • What do we want? • marbles • What do we know? • 1.00 mole marbles • 6.02 x 1023 atoms 6.02 x 1023 marbles 1.00 mole marbles 6.02 x 1023 marbles = 1 mole

  11. How many grams are in 1.00 mole of neon? • What do we want? • Grams of Ne • What do we know? • 1.00 mole Neon • 6.02 x 1023 atoms 6.02 x 1023 atoms 20.18 g Ne 1.00 mole Ne 1 mole Ne 6.02 x 1023 atoms = 20.2 g Ne

  12. 6.02 x 1023 atoms 1 mol Moles Number of Atoms 1 mol 6.02 x 1023 atoms

  13. Molar Mass 1 mol Moles Mass of 1 atom 1 mol Molar Mass

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