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The MOLE

The MOLE. Chapter # 10. The MOLE. You can measure mass, or volume, or you can count pieces. In Chemistry… We measure mass in grams. We measure volume in liters. We count pieces in ???. How Do We Measure How Much in Chemistry.

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The MOLE

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  1. The MOLE Chapter # 10

  2. The MOLE • You can measure mass, • or volume, • or you can count pieces. In Chemistry… • We measure mass in grams. • We measure volume in liters. • We count pieces in ???

  3. How Do We Measure How Much in Chemistry Counting Units: Often in an attempt to simplify the way we count, we assign special names to amounts of “things”. For example: 1 Pair of shoes = _____ shoes 1 Dozen Bagels = _____ bagels 1 Ream of Paper = ______ sheets of paper 1 Gross of Pencils = _______ pencils

  4. We choose which counting units we use based upon what the object is, how many we have and the size of the object. **Atoms are too small to be counted with Dozen and Pizzas are too large to be counted with Mole**

  5. The Chemist’s Counting Unit: The MOLE • The MOLE is another counting unit. It is used by chemists to count the number of atoms, molecules, or formula units of a chemical. • The MOLE measures an AMOUNT. • How much is a MOLE? 1 mole = # of atoms in exactly 12 g of C-12 = 6.02 X 10 23 particles or “things” = (Avogadro’s #) = 602,000,000,000,000,000,000,000 things • mol is the abbreviation for the unit mole

  6. Examples & Terminology • Covalent Compounds: 1 mol H2O = 6.02 X 1023molecules of water • Atoms: 1 mol Na = 6.02 X 1023atoms of Na • Ionic Compounds: 1 mol NaCl = 6.02 X 1023formula units of NaCl

  7. Converting Moles to Particles and Particles to Moles • You can use the mole as a conversion factor in dimensional analysis problems. • Since one mole is equal to 6.02 X 1023particles or things the conversion factors are: 1 mole__ 6.02 X 1023 6.02 X 1023 1 mole

  8. PRACTICE • How many atoms are there in 2.87 moles of Cu Metal? • If you have 2.05 X 1029 formula units of NaCl, how many moles do you have?

  9. Moles on the Periodic Table 1 H 1.0079 1 mol 6.02 x 10 23atoms 17 Cl 35.45 1 mol 6.02 x 10 23 atoms 92 U 238.0 1 mol 6.02 x 1023atoms

  10. The MASS of a MOLE Moles of substances have different masses. 1 mole of each substance has a different mass, which we will call the MOLAR MASS 1 mol of a substance = molar mass of substance (in grams)

  11. The MASS of a MOLE The molar mass of an element (from the periodic table) is the mass listed on the table: The molar mass of Aluminum = 26.98g, because its atomic mass from the table is 26.98. O = 15.99 g in 1 mol Oxygen Mg = 24.31 g in 1 mol Magnesium

  12. The MASS of a MOLE The molar mass of a compound or a molecule can be found by adding up the atomic masses of all the individual elements found in that compound/molecule. For example: Molar Mass of NaCl = mass of Na atom = 22.98 + mass of Cl atom = 35.45 58.43 g/mol

  13. The MASS of a MOLE Molar Mass K3PO4 : Mass of 3 K atoms = 3(39.09) = 117.3g Mass of 1 P atom = 30.97g + Mass of 4 O atoms = 4 (16.00) = 64.00g =212.27g/mol **212.27 grams K3PO4 in 1 mole K3PO4**

  14. PRACTICE • What is the molar mass of the following elements? • Boron • Molybdenum • Copper 2. What is the Molar Mass of the following compounds/molecules? • NaC2H4O2 • Iron (III) Sulfate • H2O • Mg (OH)2

  15. Using Molar Mass • Molar mass can be used in dimensional analysis to convert the # of moles of a substance into grams or vice versa. Molar mass conversion factors: Molar Mass of Substance (g) 1 mol of substance 1 mol of substance___ Molar mass of substance (g)

  16. Using Molar Mass • Convert 2.5 moles of Aluminum metal into grams. • Convert 75.8g of Potassium iodide into moles.

  17. Converting Mass to # of Particles Since you can convert from moles to particles and moles to mass and vice versa, you can set up dimensional analysis problems to convert from mass to particles. This only requires the addition of one more conversion factor.

  18. MASS (g) MOLES (mol) Particles (atoms or molecules)

  19. MASS (g) MOLES (mol) Particles (atoms or molecules)

  20. PRACTICE • How many atoms are present in 15.25 grams of pure lead? • What is the mass, in grams, of 5.68 X 1015 atoms of radioactive Polonium? • How many formula units are present in 99.9 g pure Copper (II) phosphate?

  21. Mole Ratios in Chemical Formulas • A chemical formula not only tells you how many of each atom are in one unit of a chemical compound, but it tells you the relative # of moles of each element in a compound. • These ratios can be used to create more conversion factors that will be used in dimensional analysis.

  22. Mole Ratios Water Molecule, H2O 1 mole of H2O = 2 Hydrogen atoms and 1 Oxygen atom are in each water molecule. Ratios: 1 mol O 1 mol H2O 2 mol H 1 molH2O 1 molH2O 1 mol O 1 molH2O 2 mol H

  23. Practice 1. How many atoms of Na are present in 3.65 moles of sodium sulfate? • How many moles of Calcium are present in 50.12 g Ca (OH)2 ?

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