1 / 22

The Mole

The Mole. What is a mole?. Mole (mol) – a counting unit. Similar to a dozen. 1 dozen is always 12. Chemists use moles to count very small objects, like atoms and molecules. 1 mole = 6.022x10 23 particles. 6.022x10 23 = 602.2 billion trillion Avogadro’s Number (N).

hea
Download Presentation

The Mole

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. The Mole

  2. What is a mole? • Mole (mol) – a counting unit. • Similar to a dozen. • 1 dozen is always 12. • Chemists use moles to count very small objects, like atoms and molecules. • 1 mole = 6.022x1023 particles. • 6.022x1023 = 602.2 billion trillion • Avogadro’s Number (N)

  3. Amadeo Avogadro (1776-1856)

  4. How Big Is Avogadro’s Number? • If you had Avogadro’s number of dollars: • you’d be 12.8 trillion times richer than Bill Gates. • you could match the entire world’s gross domestic product 11 billion times. • you could pay every person on Earth almost 90 trillion dollars (as of September 2008).

  5. Counting by Weighing – A Marble Analogy • Imagine being asked to count a small handful of green marbles. Easy, right?

  6. Counting by Weighing – A Marble Analogy • Now imagine being asked to count the marbles in a large paper bag. • You could count the marbles individually (tedious!) or... • You could find the mass of one marble, then weigh the bag of marbles and get a good estimate of how many marbles the bag contains.

  7. Counting by Weighing – A Marble Analogy • Could you count the marbles in the back of a dump truck? • You’d have to count them exclusively by weighing. • (Don’t forget to subtract the mass of the truck!)

  8. Counting by Weighing • Like the marbles in the dump truck, atoms are too numerous to count individually. • But we can estimate their numbers by weighing.

  9. Molar Mass • Molar mass (MM) – the mass of one mole of a substance in grams. • For elements, the MM is equal in number to the atomic mass.

  10. 6 1 carbon atom = 12.01 daltons (average) C 1 mol C = 12.01 grams 12.01 Molar Mass

  11. Molar Mass • What is the mass (in grams) of 4.60 mol C? 4.60 mol C 12.01 g C = 55.2 g C 1 mol C

  12. Molar Mass • How many atoms are in 4.60 mol C? 4.60 mol C 6.022x1023 atoms = 2.77x1024 atoms 1 mol C

  13. Molar Mass • Are 4.60 moles of carbon, 55.2 grams of carbon, and 2.77x1024 atoms of carbon all the same amount? • Yes!

  14. Molar Mass • How many moles are in 16.00 g He? 16.00 g He 1 mol He = 4.00 mol He 4.00 g He

  15. Molar Mass of Compounds • To find the MM of a compound: • Add the MMs of its elements. • EXAMPLE: The MM of H2O is: • 2 x H = 2 x 1.01 g/mol = 2.02 g/mol • 1 x O = 1 x 16.00 g/mol = 16.00 g/mol • TOTAL = 18.02 g/mol • 1 mol of H2O masses 18.02 g.

  16. Molar Mass of Compounds • The MM of Na2SO4 is: • 2 x Na = 2 x 22.99 g/mol = 45.98 g/mol • 1 x S = 1 x 32.07 g/mol = 32.07 g/mol • 4 x O = 4 x 16.00 g/mol = 64.00 g/mol • TOTAL = 142.05 g/mol • 1 mol of Na2SO4 masses 142.05 g.

  17. Molar Mass of Compounds • The MM of Ca(NO3)2 is: • 1 x Ca = 1 x 40.08 g/mol = 40.08 g/mol • 2 x N = 2 x 14.01 g/mol = 28.02 g/mol • 6 x O = 6 x 16.00 g/mol = 96.00 g/mol • TOTAL = 164.10 g/mol • 1 mol of Ca(NO3)2 masses 164.10 g.

  18. Molar Mass of Compounds • How many moles of CO2 are in 22.0 grams of CO2? MM of CO2 = 22.0 g CO2 1 mol CO2 1 x 12.01 g/mol = 12.01 g/mol 2 x 16.00 g/mol = 32.00 g/mol 44.01 g CO2 TOTAL = 44.01 g/mol = 0.500 mol CO2

  19. Molar Mass of Compounds • What is the mass (in grams) of 10.5 moles of SO2? MM of SO2 = 10.5 mol SO2 64.07 g SO2 1 x 32.07 g/mol = 32.07 g/mol 2 x 16.00 g/mol = 32.00 g/mol 1 mol SO2 TOTAL = 64.07 g/mol = 673 g SO2

  20. Molar Mass of Hydrates • Hydrate – an ionic cmpd that has water molecules in it. • EXAMPLES: • CuSO4•5H2O • Fe(NO3)3•9H2O • Ba(C2H3O2)2•2H2O

  21. Molar Mass of Hydrates • The MM of CuSO4•5H2O is: • 1 x Cu = 1 x 63.55 g/mol = 63.55 g/mol • 1 x S = 1 x 32.07 g/mol = 32.07 g/mol • 4 x O = 4 x 16.00 g/mol = 64.00 g/mol • 5 x H2O = 5 x 18.02 g/mol = 90.10 g/mol • TOTAL = 249.72 g/mol • 1 mol of CuSO4•5H2O masses 249.72 g.

More Related