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Moles

Moles. Text reference for moles: PP 83 to 87 and PP 237 to 249. The Mole. A number of atoms, ions, or molecules that is large enough to see and handle. A mole = number of things Just like a dozen = 12 things One mole = 6.022 x 10 23 things Avogadro’s constant = 6.022 x 10 23

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Moles

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  1. Moles • Text reference for moles: • PP 83 to 87 and • PP 237 to 249

  2. The Mole • A number of atoms, ions, or molecules that is large enough to see and handle. • A mole = number of things • Just like a dozen = 12 things • One mole = 6.022 x 1023 things • Avogadro’s constant = 6.022 x 1023 • Symbol for Avogadro’s constant is NA.

  3. The Mole • How do we know when we have a mole? • count it out • weigh it out • Molar mass - mass in grams numerically equal to the atomic weight of the element in grams. • H has an atomic weight of 1.00794 g • 1.00794 g of H atoms = 6.022 x 1023 H atoms • Mg has an atomic weight of 24.3050 g • 24.3050 g of Mg atoms = 6.022 x 1023 Mg atoms

  4. The Mole • Example 2-1: Calculate the mass of a single Mg atom in grams to 3 significant figures.

  5. The Mole • Example 2-1: Calculate the mass of a single Mg atom in grams to 3 significant figures.

  6. The Mole • Example 2-1: Calculate the mass of a single Mg atom in grams to 3 significant figures.

  7. The Mole • Example 2-1: Calculate the mass of a single Mg atom, in grams, to 3 significant figures.

  8. The Mole • Example 2-2: Calculate the number of atoms in one-millionth of a gram of Mg to 3 significant figures.

  9. The Mole • Example 2-2: Calculate the number of atoms in one-millionth of a gram of Mg to 3 significant figures.

  10. The Mole • Example 2-2: Calculate the number of atoms in one-millionth of a gram of Mg to 3 significant figures.

  11. The Mole • Example 2-2: Calculate the number of atoms in one-millionth of a gram of Mg to 3 significant figures.

  12. The Mole • Example 2-3. How many atoms are contained in 1.67 moles of Mg?

  13. The Mole • Example 2-3. How many atoms are contained in 1.67 moles of Mg?

  14. The Mole • Example 2-3. How many atoms are contained in 1.67 moles of Mg?

  15. The Mole • Example 2-3. How many atoms are contained in 1.67 moles of Mg?

  16. The Mole • Example 2-3. How many atoms are contained in 1.67 moles of Mg?

  17. The Mole • Example 2-4: How many moles of Mg atoms are present in 73.4 g of Mg? You do it!

  18. The Mole • Example 2-4: How many moles of Mg atoms are present in 73.4 g of Mg?

  19. The Mole • Example 2-4: How many moles of Mg atoms are present in 73.4 g of Mg?

  20. The Mole • Example 2-4: How many moles of Mg atoms are present in 73.4 g of Mg? IT IS IMPERATIVE THAT YOU KNOW HOW TO DO THESE PROBLEMS

  21. Formula Weights, Molecular Weights, and Moles • How do we calculate the molar mass of a compound? • add atomic weights of each atom • The molar mass of propane, C3H8, is: • 3C X 12.01g = 36.03g • 8H X 1.01g = 8.08g • 44.11 g/mole

  22. Formula Weights, Molecular Weights, and Moles • The molar mass of calcium nitrate, Ca(NO3)2 , is: You do it!

  23. Formula Weights, Molecular Weights, and Moles • One Mole of Contains • Cl2 or 70.90g 6.022 x 1023 Cl2 molecules 2(6.022 x 1023 ) Cl atoms • C3H8You do it!

  24. Formula Weights, Molecular Weights, and Moles • One Mole of Contains • Cl2 or 70.90g 6.022 x 1023 Cl2 molecules 2(6.022 x 1023 ) Cl atoms • C3H8 or44.11 g 6.022 x 1023 C3H8 molecules 3 (6.022 x 1023 ) C atoms 8 (6.022 x 1023 ) H atoms

  25. Formula Weights, Molecular Weights, and Moles • Example 2-5: Calculate the number of C3H8 molecules in 74.6 g of propane.

  26. Formula Weights, Molecular Weights, and Moles • Example 2-5: Calculate the number of C3H8 molecules in 74.6 g of propane.

  27. Formula Weights, Molecular Weights, and Moles • Example 2-5: Calculate the number of C3H8 molecules in 74.6 g of propane.

  28. Formula Weights, Molecular Weights, and Moles • Example 2-5: Calculate the number of C3H8 molecules in 74.6 g of propane.

  29. Formula Weights, Molecular Weights, and Moles • Example 2-6. What is the mass of 10.0 billion propane molecules? You do it!

  30. Formula Weights, Molecular Weights, and Moles • Example 2-6. What is the mass of 10.0 billion propane molecules?

  31. Formula Weights, Molecular Weights, and Moles • Example 2-7. How many (a) moles, (b) molecules, and (c) oxygen atoms are contained in 60.0 g of ozone, O3? The layer of ozone in the stratosphere is very beneficial to life on earth. You do it!

  32. Formula Weights, Molecular Weights, and Moles • Example 2-7. How many (a) moles, (b) molecules, and (c) oxygen atoms are contained in 60.0 g of ozone, O3? The layer of ozone in the stratosphere is very beneficial to life on earth. (a)

  33. Formula Weights, Molecular Weights, and Moles • Example 2-7. How many (a) moles, (b) molecules, and (c) oxygen atoms are contained in 60.0 g of ozone, O3? The layer of ozone in the stratosphere is very beneficial to life on earth. (b)

  34. Formula Weights, Molecular Weights, and Moles • Example 2-7. How many (a) moles, (b) molecules, and (c) oxygen atoms are contained in 60.0 g of ozone, O3? The layer of ozone in the stratosphere is very beneficial to life on earth. (c)

  35. Formula Weights, Molecular Weights, and Moles • Example 2-8. Calculate the number of O atoms in 26.5 g of Li2CO3. You do it!

  36. Formula Weights, Molecular Weights, and Moles • Example 2-8. Calculate the number of O atoms in 26.5 g of Li2CO3.

  37. Percent Composition and Formulas of Compounds • % composition = mass of an individual element in a compound divided by the total mass of the compound x 100% • Determine the percent composition of C in C3H8.

  38. Percent Composition and Formulas of Compounds • What is the percent composition of H in C3H8? You do it!

  39. Percent Composition and Formulas of Compounds • What is the percent composition of H in C3H8?

  40. Percent Composition and Formulas of Compounds • Example 2-10: Calculate the percent composition of Fe2(SO4)3 to 3 significant figures. You do it!

  41. Percent Composition and Formulas of Compounds • Example 2-10: Calculate the percent composition of Fe2(SO4)3 to 3 sig. fig.

  42. Derivation of Formulas from Elemental Composition • Example 2-11: A compound contains 24.74% K, 34.76% Mn, and 40.50% O by mass. What is its empirical formula? • Make the simplifying assumption that we have 100.0 g of compound. • In 100.0 g of compound there are: • 24.74 g of K • 34.76 g of Mn • 40.50 g of O

  43. Derivation of Formulas from Elemental Composition

  44. Derivation of Formulas from Elemental Composition

  45. Derivation of Formulas from Elemental Composition

  46. Derivation of Formulas from Elemental Composition

  47. Derivation of Formulas from Elemental Composition

  48. Derivation of Formulas from Elemental Composition • Example 2-12: A sample of a compound contains 6.541g of Co and 2.368g of O. What is the empirical formula for this compound? You do it!

  49. Derivation of Formulas from Elemental Composition • Example 2-12: A sample of a compound contains 6.541g of Co and 2.368g of O. What is the empirical formula for this compound?

  50. Derivation of Formulas from Elemental Composition • Example 2-12: A sample of a compound contains 6.541g of Co and 2.368g of O. What is the empirical formula for this compound?

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