Ch. 10

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Molar Conversions

• Ch. 10 The Mole

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A. What is the Mole?

• A counting number (like a dozen)
• Avogadros number (NA)
• 1 mol 6.02 ? 1023 items

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A. What is the Mole?
HOW LARGE IS IT???

• 1 mole of hockey pucks would equal the mass of
  the moon!

• 1 mole of basketballs would fill a bag the size
  of the earth!

• 1 mole of pennies would cover the Earth 1/4 mile
  deep!

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B. Molar Mass

• is the mass of 1 mole of an element or
  compound.
• Atomic mass on the periodic table tells both
  the...
• atomic mass units per atom (amu)
• grams per mole (g/mol)
• Round to 2 decimal places

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B. Molar Mass Examples

• 1 atom carbon 12.01 amu
• 1 atom aluminum 26.98 amu
• 1 atom zinc 65.39 amu

12.01 g/mol 26.98 g/mol 65.39 g/mol
1 mole carbon 1 mole aluminum 1mole zinc
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B. Molar Mass Calculations
Multiply the subscript by the element mass
preceding it, then sum up all total masses. If
in parentheses, subscript is multiplied by all
other internal subscripts.

• H2O water
• 2(1.01) 16.00 18.02 g/mol
• NaCl sodium chloride
• 22.99 35.45 58.44 g/mol

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B. Molar Mass Examples

• sodium bicarbonate
• sucrose

• NaHCO3
• 22.99 1.01 12.01 3(16.00) 84.01
  g/mol
• C12H22O11
• 12(12.01) 22(1.01) 11(16.00) 342.34
  g/mol

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C. Molar Conversions
changing between quantities of mass (big), moles
(the converter), and molecules (tiny).
molar mass
6.02 ? 1023
(g/mol)
(particles/mol)
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C. Molar Conversion Examples

• How many moles of carbon are in 26 g of carbon?

26 g C
1 mol C 12.01 g C
2.2 mol C
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C. Molar Conversion Examples

• How many molecules are in 2.50 moles of
  C12H22O11?

6.02 ? 1023 molecules 1 mol
2.50 mol
1.51 ? 1024 molecules C12H22O11
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C. Molar Conversion Examples

• Find the mass of 2.1 ? 1024 atoms of iron. The
  atomic mass of Fe is 55.8amu, so 1 mole of Fe
  will weigh 55.8 GRAMS.

2.1 ? 1024 atoms
1 mol 6.02 ? 1023 atoms
55.8g Fe 1 mol
55.8g Fe
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C. Molar Conversion Examples

• Find the mass of 2.1 ? 1024 molecules of NaHCO3.

2.1 ? 1024 molecules
1 mol 6.02 ? 1023 molecules
84.01 g 1 mol
290 g NaHCO3