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Masses and moles

Masses and moles. Not that kind of mole. Re-mem-mem Re-mem-mem-member…. 19. 39.0983. K. Average atomic mass, in amu/atom. Potassium. Re-mem-mem Re-mem-mem-member…. 19. 39.0983. K. Assume the most common isotope has 39 p+n (19p and 20n)—but there are some heavier ones. Potassium.

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Masses and moles

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  1. Masses and moles Not that kind of mole

  2. Re-mem-memRe-mem-mem-member… 19 39.0983 K Average atomic mass, in amu/atom Potassium

  3. Re-mem-memRe-mem-mem-member… 19 39.0983 K Assume the most common isotope has 39 p+n (19p and 20n)—but there are some heavier ones. Potassium

  4. And now, for something completely different. • Def: 1 mole=6.02 x 1023 particles Not that kind of mole

  5. As a conversion factor • 2.7 moles Ar = _?_atoms Ar • 1.5 x 1021 molecules H2O=__?__moles H2O .

  6. As a conversion factor • 2.7 moles Ar = _?_atoms Ar 2.7 moles Ar x 6.02 x 1023 atoms Ar= 1 mole Ar • 1.5 x 1021 molecules H2O=__?__moles H2O 1.5 x 1021 molecules H2O x 1mole H2O = 6.02 x 1023molecules H2O

  7. As a conversion factor • 2.7 moles Ar = _?_atoms Ar 2.7 moles Ar x 6.02 x 1023 atoms Ar= 1 mole Ar • 1.5 x 1021 molecules H2O=__?__moles H2O 1.5 x 1021 molecules H2O x 1mole H2O = 6.02 x 1023molecules H2O 1.6 x 1024 atoms Ar .0025 moles H20

  8. 6.02 x 1023

  9. 6.02 x 1023 • Avogadro’s number. • Amadeo Avogadro. • He suggested that there is a number. • The number is larger than he expected.

  10. The greatest conversion of all time! 1 amu X 6.02 x 1023 = 1 gram atom X 6.02 x 1023 mole Avogadro’s number!

  11. Avogadro’s number is also the conversion from amu’s to grams. • Both sets of units define the mole.

  12. What is the mass? • .0582 mol Ni • 12.0 mol Ne • 4.80 x 10 25 atoms Xe • 1.24 x 10 21 atoms Au

  13. What is the mass? • .0582 mol Ni • 12.0 mol Ne • 4.80 x 10 25 atoms Xe • 1.24 x 10 21 atoms Au Convert to moles first!

  14. What is the mass? • .0582 mol Ni 3.42 g Ni • 12.0 mol Ne 242 g Ne • 4.80 x 10 25 atoms Xe 10500 g Xe • 1.24 x 10 21 atoms Au .406 g Au

  15. What is the mass? • 2.4 mol He • 9.03 x 10 23 atoms K

  16. How many moles? • 18.3 g Sr • 4.8 g Ar • 4.03 x 10 23 formula units of iron (III) oxide • 7.24 x 10 21 molecules sulfur hexaflouride

  17. How many moles? • 18.3 g Sr .209 mol Sr • 4.8 g Ar .12 mol Ar • 4.03 x 10 23 formula units of iron (III) oxide .669 mol Fe2O3 • 7.24 x 10 21 molecules sulfur hexaflouride .012 mol SF6

  18. How many moles? • .130 g Ag • 1.42 x 10 24 molecules nitrogen trichloride

  19. Pop quiz • If 1 mole of hydrogen atoms (H) has a mass of 1.0078 g, what is the mass of 1 mole of hydrogen molecules (H2)?

  20. Pop quiz • If 1 mole of hydrogen atoms (H) has a mass of 1.0078 g, what is the mass of 1 mole of hydrogen molecules (H2)? • I hope you answered “Twice that mass.”, or 2.0156 g

  21. Formula masses • If I give you a formula, you add the masses of the atoms represented to get the formula mass. • The units are grams/mole

  22. What is the formula mass of… • LiCl • BaF2 • K2SO3 • Fe2(Cr2O7)3 • Na2HPO4 • 7H2O

  23. What is the formula mass of… • Gold (I) fluoride • Lithium oxide • Cobalt (II) cyanide • dinitrogen trisulfide • tetraphosphorus hexoxide

  24. PS • The subscripts in a formula can be read: K2SO3 There are two potassium atoms in a formula unit of potassium sulfite There are two moles of potassium in a mole of potassium sulfite or

  25. PS • The standard molar volume for a gas is: at STP 22.4L/mol 22.4L/mol STP =standard temperature and pressure = 273k, 1.00 atm

  26. PS is about 22.4 L

  27. Mole conversions

  28. Mole conversions Mass Moles

  29. Mole conversions Mass Moles Use the formula mass

  30. Mole conversions Mass Moles FM in grams = 1 mole

  31. Mole conversions Particles Moles

  32. Mole conversions Particles Moles Use Avogadro’s number

  33. Mole conversions Particles Moles 6.02 x 10 23 particles = 1 mole

  34. Mole conversions Volume of a gas at STP Moles

  35. Mole conversions Volume of a gas at STP Moles Use the molar volume

  36. Mole conversions Volume of a gas at STP Moles 22.4 L gas at STP = 1 mole

  37. Mole conversions Particles Use Avogadro’s number Use the molar volume Moles Use the formula mass Volume of a gas at STP Mass

  38. Styrene: an organic molecule, C8H8 • What is the molecular weight of styrene? • What is the empirical formula of styrene? • How much does 1.000 mole of styrene weigh? • How much does 1.54 pmole of styrene weigh? • How much many moles in 9.67 kg of styrene? • How many moles in 84.6 mg of styrene?

  39. Styrene: an organic molecule, C8H8 • What is the mass % of C in styrene? • What is the mass % of H in styrene? • An unknown material is recovered from the Delaware River. Results from analysis of it are Carbon 92.26% Hydrogen7.74% Is it styrene? • The molecular weight of this compound is 78.11 grams per mole. What is its molecular formula?

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