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THE MOLE

THE MOLE. you know that certain quantities can be represented by various terms: dozen = pair = these terms make counting easier. 12. 2. Chemists need method for counting atoms in a sample Why? So there is a term for counting atoms or molecules……………….

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THE MOLE

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  1. THE MOLE

  2. you know that certain quantities can be represented by various terms: dozen = pair = • these terms make counting easier 12 2

  3. Chemists need method for counting atoms in a sample • Why? • So there is a term for counting atoms or molecules……………….. Because atoms are small and there is an extremely large number to count

  4. The Mole • Defn – SI unit for measuring amount of substances • What is the value of mole? 1 mole = 6.022 x 1023 particles particles is whatever: atoms, molecules,etc Avogadro’s number

  5. The Mole • Conversion factor 1 mole 6.022 x 1023 particles 6.022 x 1023 particles 1 mole

  6. The Mole • 1 mole is a HUGE FREAKIN’ NUMBER!!!! • The distance from earth to sun is 93 million miles. • 1 mole of stacked paper can make that trip more than one million times!!

  7. Mole Problems 1) How many atoms of zinc in 2.50 moles of zinc? 2.50 mole Zn 6.022 x 1023 atoms Zn 1 mole Zn = 1.51 x 1024 atoms

  8. Mole Problems 1) How many molecules of sucrose in 3.5 moles of sucrose? 3.5 mole sucrose 6.022 x 1023 molecules sucrose 1 mole sucrose = 2.11 x 1024 molecules

  9. Mole Problems • Calculate the number of moles in 5.75 x 1024 atoms of aluminum. 5.75 x 1024 atoms Al 1 mole Al 6.022 x 1023 atoms Al = 9.55 mole Al

  10. Question 1 dozen eggs 1 dozen doughnuts 1 dozen cokes 1 dozen cars 1 dozen computers 1 dozen elephants 1 dozen shoes Do all these have the same mass?

  11. Question 1 mole copper 1 mole silver 1 mole hydrogen 1 mole gold 1 mole uranium 1 mole lead 1 mole iron Do all these have the same mass?

  12. Why does 1 mole of different substances have different masses? 1) different size 2) different composition Mass of 1 mole Fe ≠ mass of 1 mole Cu

  13. Molar Mass • Defn – mass, in grams, of one mole of a substance • Unit: g mol

  14. Molar Mass • What is the molar mass of nitrogen? • What is the molar mass of oxygen? 7 14.0 g N 1 mol 14.01 8 16.0 g O 1 mol 15.99

  15. Example Problems 1) What is the mass of 3.57 moles Al? mol  g 13 3.57 mol Al 27.0 g Al Al = 96.3 g Al 1 mol Al 27.0 Molar mass Al

  16. Example Problems 2) Calculate the mass of 4 moles of oxygen. mol  g 8 4 mol O 16.0 g O O = 64 g O 1 mol O 15.99 Molar mass O

  17. Example Problems 3) How many moles in 43.5 g sulfur? g  mol 16 S 32.06 43.5 g S 1 mol S = 1.36 mol S 32.1 g S Molar mass S

  18. Example Problems 3) How many moles in 28.5 g nitrogen? g  mol 7 N 14.01 28.5 g N 1 mol N = 2.04 mol N 14.0 g N Molar mass N

  19. Putting it all together Avogadro’s number Molar Mass particles grams moles

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