1 / 126

Understanding the Mole: A Precise Unit of Measure for Atoms and Compounds

Learn about the concept of a mole, its importance in chemistry, and how to convert between moles and particles. Discover the molar mass of elements and compounds. Suitable for students and chemistry enthusiasts.

Download Presentation

Understanding the Mole: A Precise Unit of Measure for Atoms and Compounds

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? • It’s a precise number of things • Its similar to the concept of a dozen • A dozen eggs = 12 eggs • A mole = 6.02 X 1023 • Mole in latin = heap or pile

  3. Why do we use a mole? • Atoms are very small • You can’t see an atom • You cant see a dozen atoms not even a billion atoms • But if you had a mole of atoms now you can start to see them and weigh them

  4. How BIG is a Mole? • A mole of water is 18 ml • A mole of marbles would…?

  5. How BIG is a Mole? • A mole of water is 18 ml • A mole of marbles would cover the entire earth several miles deep

  6. How big is a mole? one mole of table tennis balls would cover the Earth to a depth of about 40 km.

  7. Counting atoms by weighing? • Atoms are too small to count individually • We count atoms by weighing them • A mole of carbon weighs 12.01 g

  8. Counting atoms by weighing? • Ex. imagine you work in a candy store and people wanted to buy 50 jelly beans or 300 or even 1000 jelly beans • instead of counting each jelly bean you could find out what 1 jelly bean weighs then multiply by the number you needed • ex. 1 jelly bean = 1 gram 500 JB = 500g

  9. Counting atoms by weighing? • 1 jelly bean = 1 gram • The customer wants 1000 jelly beans • 1000 beans x 1 grams = 1000 grams 1 jelly bean It’s a lot easier to weigh out 1000 g of jelly beans on a scale then count each one by hand

  10. The MOLE • Mole- SI unit for amount of matter • mol • 6.02 X 1023 representative particles • Avogadro’s number = 6.02 X 1023

  11. The MOLE • Mole- SI unit for amount of matter • mol • 6.02 X 1023 representative particles = Avogadro’s Number . Atom (Fe, C) • Molecule (molecular compounds; CH4) • Formula Units (salts, ionic compounds; NaCl) • Ions (Na+)

  12. 1 mole = 6.02 X 1023 particles : 6.02 X 1023 particles 1mol 0r 1mol . 6.02 X 1023 particles

  13. 1 mole = the atomic mass of an element in grams • Gram atomic mass is the atomic mass from the periodic table, expressed as “grams/mole” instead of “amu”

  14. 1 mole = the atomic mass of an element in grams • Gram atomic mass is the atomic mass from the periodic table, expressed as “grams/mole” instead of “amu” • Ex. 1 mole of Carbon has a mass of 12.01 g 1 mol Carbon12.01 g Carbon 12.01 g Carbon OR 1 mol Carbon

  15. Molar mass is the mass in grams of one mole of a substance. • It’s value comes from the periodic table. • Molar mass is related to Avogadro’s number like this: Molar mass (g) = 1mole = 6.02x1023 particles

  16. Elements For Zn, 1mol=65.39g For Al, 1mol=26.98g For Au, 1mol=196.97g Don’t forget the diatomics!! For O2, 1mol=32.00g Examples relating mass and moles

  17. Compounds For NaCl, 1 mol=(22.99+35.45)g For H2O, 1mol=((2x1.01)+16.00)g For C2H6, 1mol=((2x12.01)+(6x1.01))g Examples relating mass and moles

  18. Be able to convert from moles to particles: • How many molecules are in 0.360 mol of water?

  19. Be able to convert from moles to particles: • How many molecules are in 0.360 mol of water? 1st write given: 0.360 mol H2O x 1

  20. Be able to convert from moles to particles: • How many molecules are in 0.360 mol of water? 2nd write conversion factor: 0.360 mol H2O x 6.02 X 1023 molecules = 1 1mol H20

  21. Be able to convert from moles to particles: • How many molecules are in 0.360 mol of water? Next multiply everything on top divide by everything on the bottom: 0.360 mol H2O x 6.02 X 1023 particles = 1 1mol

  22. Be able to convert from moles to particles: • How many molecules are in 0.360 mol of water? Next multiply everything on top divide by everything on the bottom: 0.360 mol H2O x 6.02 X 1023 particles = 1 1mol Answer = 2.17 E23 molecules of water

  23. Be able to convert from particles to moles: • How many moles of Mg are in 1.25 X1023 atoms?

  24. Be able to convert from particles to moles: • How many moles of Mg are in 1.25 X1023 atoms? Write given then conversion factor 1.25 X1023 atoms Mg x 1 mol Mg = 1 6.02 X 1023 atoms

  25. Be able to convert from particles to moles: • How many moles of Mg are in 1.25 X1023 atoms? Write given then conversion factor 1.25 X1023 atoms Mg x 1 mol = 1 6.02 X 1023 atoms Answer = .208 moles of Mg

  26. Find the molar mass 1 mol C = 1 mol CH4 = 1 mol (NH4)2CO3 1 mol CaCl2 =

  27. Find the molar mass 1 mol C = 12.01 g/mol 1 mol CH4 = 16.05 g/mol 1 mol (NH4)2CO3 = 98.11 g/mol 1 mol CaCl2 = 110.98 g/mol

  28. 4.65 X 1024 molecules NO2 1 Ex. How many moles are in 4.65 X 1024 molecules of NO2?

  29. 4.65 X 1024 molecules NO2 x 1 mole NO2 = 1 6.02x1023 molecules Ex. How many moles are in 4.65 X 1024 molecules of NO2?

  30. 4.65 X 1024 molecules NO2 x 1 mole NO2 = 1 6.02x1023 molecules Answer = 7.72 moles NO2 Ex. How many moles are in 4.65 X 1024 molecules of NO2?

  31. Molar Mass- mass of 1 mol in g, • use periodic table & add up the masses, • round to 2 spaces past the decimal

  32. Molar Mass- mass of 1 mol in g, • use periodic table & add up the masses, • round to 2 spaces past the decimal Find Molar Mass of: Ne Cl2 NH3

  33. Molar Mass- mass of 1 mol in g, • use periodic table & add up the masses, • round to 2 spaces past the decimal Find Molar Mass of: Ne = 20.18 g Cl2 = 35.45 x 2 = 70.90 g NH3 = 14.01 + 3(1.01) = 14.01 + 3.03 = 17.04g

  34. Be able to convert moles to mass: • Use the following conversion factor: Molar mass (g) 1 mol

  35. Be able to convert moles to mass: • Use the following conversion factor: Molar mass (g) 1 mol • How many g are in 9.45 mol N2O3? First find Molar Mass N2O3 2(14.01) + 3(16.00) = 28.02 +48.00 =76.02 g

  36. Be able to convert moles to mass: • Use the following conversion factor: Molar mass (g) 1 mol • How many g are in 9.45 mol N2O3? 9.45 mol N2O3 x 76.02 g N2O3 = ??? 1 mol N2O3

  37. Be able to convert moles to mass: • Use the following conversion factor: Molar mass (g) 1 mol • How many g are in 9.45 mol N2O3? 9.45 mol N2O3 x 76.02 g N2O3 = 718.39 g 1 mol N2O3

  38. Be able to convert mass to moles: • Multiply by: 1 mol Molar mass (g)

  39. Be able to convert mass to moles: • Multiply by: 1 mol Molar mass (g) How many moles are in 92.2 g Fe2O3?

  40. Be able to convert mass to moles: • Multiply by: 1 mol Molar mass (g) How many moles are in 92.2 g Fe2O3? 92.2 g Fe2O3 X 1 MoleFe2O3 = g Fe2O3

  41. Be able to convert mass to moles: • Multiply by: 1 mol Molar mass (g) How many moles are in 92.2 g Fe2O3? Molar Mass Fe2O3 = 2(55.85g) + 3(16.00g)= 111.70 + 48.00 =159.7

  42. Be able to convert mass to moles: • Multiply by: 1 mol Molar mass (g) How many moles are in 92.2 g Fe2O3? 92.2 g Fe2O3 X 1 MoleFe2O3 = 159.7 g Fe2O3

  43. Be able to convert mass to moles: • Multiply by: 1 mol Molar mass (g) How many moles are in 92.2 g Fe2O3? 92.2 g Fe2O3 X 1 MoleFe2O3 = 159.7 g Fe2O3 Answer = 0.577 moles Fe2O3

  44. Multi-step problems- convert to moles then to desired unit • Calculate number of molecules in 60.0g NO2. 60.0g NO2 x 1 mole NO2 46.01 g NO2

  45. Multi-step problems- convert to moles then to desired unit • Calculate number of molecules in 60.0g NO2. 60.0g NO2 x 1 mole NO2 x 6.02x1023 molecules 46.01 g NO2 1 mole NO2

  46. Multi-step problems- convert to moles then to desired unit • Calculate number of molecules in 60.0g NO2. 60.0g NO2 x 1 mole NO2 x 6.02x1023 molecules 46.01 g NO2 1 mole NO2 Answer = 7.85 x 1023 molecules of NO2

  47. Lab Counting by weighing

  48. For all substances: • 1 mol=molar mass=6.02 X 1023 particles • FOR GASES ONLY: • 1 mol=molar mass=6.02 X 1023 particles • AND at STP (standard temperature & pressure) OC &101.3kpa or 1 atm 1mol= 22.4L • Molar volume- 1 mol of gas at STP has 22.4 L

  49. Convert mol volume • Multiply by: 22.4L 1 mol • Determine the volume of 0.60 mol SO2 at STP. • To convert from volumemol invert the conversion factor • Determine the number of moles in 2 L of CO2 gas at STP.

  50. Can also use density to solve problems • D=mass/volume= m/v=g/L • D of a gas containing C & O is 1.964 g/L at STP. Determine that molar mass. • What is the density of krypton gas at STP?

More Related