The%20Mole

1
The Mole

• The amount of a substance that contains
• 6.02 x 1023 particles.

• 602,000,000,000,000,000,000,000
• Avogadros Number

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The Mole

• The abbreviation for mole is

mol
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Molar Mass

• Molar mass of an element mass in grams (g) of a
  mole of atoms of that element.
• Ex. C 12.0 g, H 1.0 g, O 16.0 g
• You can read this on your periodic table. It
  represents the average atomic mass (in grams) of
  a mole of atoms of the element.

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Molar Mass of a Compound

• Simply requires basic multiplication and
  addition.
• Ex. What is the molar mass of water, H2O?
• 1 mole of water has 2 moles of hydrogen and 1
  mole of oxygen.
• 2 mole ? H at 1.0 g/mol 2.0 g H
• 1 mole ? O at 16.0 g/mol 16.0 g O
• 2.0 g 16.0 g 18.0 g/mol

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Find the molar mass of Al2(SO4)3

• 1 mole of Al2(SO4)3 has 2 moles of aluminum, 3
  moles of sulfur, and 12 moles of oxygen.
• Molar mass of Al 27.0 g/mol
• Molar mass of S 32.1 g/mol
• Molar mass of O 16.0 g/mol
• 2 x (27.0 g/mol) 3 x (32.1 g/mol) 12 x (16.0
  g/mol)
• 342.3 g/mol

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Molar Mass as a Conversion Factor

• The molar mass of H2O 18.0 g/mol
• This means 1 mole H2O 18.0 g H2O
• Therefore, we can turn this into two conversion
  factors.
• 18.0 g 1 mole
• 1 mole 18.0 g

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Mole Conversions

• moles ? grams Use Molar Mass
• grams ? moles
• Moles ? grams
• Ex. What is the mass of 3.0 moles Carbon?

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Mole Conversions (moles ? grams)

• Ex. What is the mass of 3.0 moles Carbon?
• One mole of carbon weighs 12.0 g
• Three moles of carbon weighs 3 x 12.0 g
• 36.0 g

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Mole Conversions (moles ? grams)
What is the mass of 4.5 moles of H2O?
One mole of H2O 1.0g (H) 1.0g (H) 16.0g
(O) 18.0g
4.5 moles of H2O 4.5 x 18.0g 81.0g
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Mole Conversions (grams ? moles)
How many moles is 44.5 g H2O?
One mole of H2O 1.0g (H) 1.0g (H) 16.0g
(O) 18.0g/mol
44.5g 18.0g/mol
2.47 mol H2O
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Mole Conversions (grams ? moles)
How many moles is 2.5 g NaCl?
One mole of NaCl 22.99g (Na) 35.45g (Cl)
58.44g/mol
2 sig. digs.
2.5g 58.44g/mol
.04 mol NaCl
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molecules/atoms ? molesmoles ? molecules/atoms

• Use Avogadros
• 6.02 x 1023 moles/atoms
• mole
• Ex. Molecules ? moles
• How many moles is 9.00 x 1023 molecules of CO2?

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molecules/atoms ? moles

• How many moles is 9.00 x 1023 molecules of CO2?

9.00 x 1023 molecules 6.02 x 1023 molecules
1.50 mole of CO2
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Moles ? molecules/atoms How many molecules is
1.75 moles H2O?
1.75mole x 6.02 x 1023 atoms x 1 molecule H2O
mole 3 atoms
3.51 x 1023 molecules H2O
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Combining Steps
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How many molecules is 50.0 g H2O? What is the
mass of 9.0 x 1023 molecules of CO2?