The Mole

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The Mole
Chapter11
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I. Atoms, Molecules, and Formula units
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I. Atoms, Molecules, and Formula units

• The terms atom, molecule, and formula units can
  be used to represent very similar things.

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Atoms

• The term atoms is used to describe units of
  uncombined elements from the periodic
  table.Examples O, U, Zr, and Ag are all atoms
  (no subscripts)

O
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Metals Non-Metals
Non-Metals
Metals!
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Molecules

• The term molecule is used to describe a molecular
  compound. This is any compound that contains only
  non-metals in its formula. Non-metals are found
  on the right side of the staircase on the
  periodic table, and also includes
  Hydrogen.Examples S8, N2O2, O3, and CO2are all
  molecules (all non-metals, more than one atom
  in the formula)

C
O
O
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Formula Units

• The term formula units are used to describe any
  unit of an ionic compound, which is any compound
  that contains a metal in its formula. Metals can
  be found on the left side of the staircase on a
  periodic table. Ex. CaO, NaI, and AgNO3 are all
  formula units (metal in the formula, more than
  one atom in the formula)

O
Ca
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• The term formula units is long, so well call it
  FUN. We could abbreviate with just the first
  letter of each word, but that can easily be
  misinterpreted as something else yikes, we dont
  want that do we?

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• Remember, a compound, molecular or ionic, is made
  up of at least 2 atoms from the periodic table.

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Atom, Molecule or FUN?

1. H2O
2. Mg
3. NaNO3
4. Cl2
5. Ne
6. Sc
7. KCl

molecule
atom
Formula Unit
molecule
atom
atom
Formula Unit
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I. The mole and Avogadros number
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What is a mole?

• A machine that bores through hard surfaces, used
  especially for tunneling through rock.
• A spy who operates from within an organization,
  especially a double agent operating against his
  or her own government from within its
  intelligence establishment.

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An animal
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(No Transcript)
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A birth mark
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In Chemistry

• From the atomic structure unit we learned that 1
  atom of any element is equal to the atomic mass
  on the periodic table.
• The units for atomic mass is amu (atomic mass
  unit)

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• Example 1 atom of hydrogen 1.008 amu of
  hydrogen

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• However, in a laboratory it would be difficult to
  work with atoms, since they are so small
• Instead we use the same atomic masses on the
  periodic table, but use the units of grams (per
  mole)

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• Example 1 mole of hydrogen 1.008 grams of
  hydrogen

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• The value of the mole was experimentally defined
  by the number of carbon atoms in 12.01 grams of
  carbon. There are 6.02 x 1023 atoms of carbon in
  12.01 grams of carbon.
• 6.02 x 1023 is referred to as Avogadros number.
  It represents a specific amount of something.

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Its really just a word to represent a number
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Just like

• a couple of cookies __2__ cookies
• a dozen doughnuts _12_ doughnuts
• a gross of geese __144___ geese

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• a mole of mints 6.02 x 1023 mints
• a mole of basketballs 6.02 x 1023
  basketballs
• a mole of marshmallows 6.02 x 1023
  marshmallows

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• "mole" represents the number 6.0221367 x 1023 or
  602000000000000000000000

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Although a mole can be used to describe any type
of object, it is usually limited to subatomic
particles.

• a mole of atoms 6.02 x 1023 atoms
• a mole of molecules 6.02 x 1023 molecules
• a mole of formula units 6.02 x 1023 formula
  units

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• A mole of anything can be difficult to imagine. A
  mole of marbles is enough to cover the earth to a
  depth of 50 miles! Whoa, thats a lot of marbles.

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A mole of atoms 6.02 x 1023 atoms A mole of
molecules 6.02 x 1023 molecules A mole of
formula units 6.02 x 1023 formula units

• Although a mole can be used to describe any type
  of object, it is usually limited to subatomic
  particles.

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In your box

• 1 mole
• 6.02 X 1023 atoms, molecules, or formula units

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Three ways of representing amounts

• 12 large eggs
• 1 dozen eggs
• 24 ounces of eggs

• 6.02 X 1023 Iron atoms
• 1 mole of iron atoms
• 55.847 grams of iron

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Fun Facts

• It is often referred to as Avogadro's number (in
  honor of Amedeo Avogadro)
• Mole is derived from the Latin word moles,
  which means a mass
• Molecule is the diminutive form of this word
  that means a small mass

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Mole day is generally celebrated on October 23
1023 AT 602AMget it?
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To compare.

• A dozen of eggs will fit in an egg carton
• A mole of eggs will fill all the oceans on the
  earth more than 30 million times over
• It would take 10 billion chickens laying 10 eggs
  per day more than 10 billion years to lay a mole
  of eggs

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Why use such a big number?

• We use moles when it comes to atoms and
  molecules
• take a guess?

Because atoms are so small
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B. Calculating with Avogadros Number

• Remember, Avogadros number is an equality and
  you can make 2 conversion factors out of it. Use
  dimensional analysis to determine the
  information you are seeking.

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The two conversion factors
1 mol___ 6.02 x 1023
6.02 x 1023 1 mole
and
atoms, molecules, or formula units
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EX 1 Determine the moles of magnesium there are
in 1.23 x 1024 atoms of magnesium
G 1.23 x 1024 atoms Mg W moles Mg R 1 mole Mg
6.02 x 1023 atoms Mg
1.23 x 1024 atoms Mg
1 mole Mg
6.02 x 1023 atoms Mg
1
2.04
mol Mg
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EX 2 Determine the number of atoms in 8.93 moles
of argon.
8.93 moles Ar
6.02 x 1023 atoms Ar
1 mole Ar
1
5.38 x 1024
Atom Ar
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Ex 3 Determine the number of water molecules in
11.2 moles of water.
11.2 moles H2O
6.02 x 1023 molecules H2O
1 moles H2O
1
6.74 x 1024
molecules H2O
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Practice Box
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Practice

• 1.
• 2.
• 3.

3.37 x 1022
Atoms Pu
19.9
Moles of Phosphorus
87.0
Moles CCl4
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1. Determine the number of atoms in 0.056 mol of
plutonium
0.056 mol Pu
6.02 x 1023 atoms Pu
1 mole Pu
1
3.37 x 1022
Atoms Pu
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2. How many moles are in 1.20 x 1025 atoms of
phosphorus?
1.20 x 1025 atoms P
1 mole P
6.02 x 1023 atoms P
1
19.9
Moles of Phosphorus
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3. How many moles are in 5.24 x 1025 molecules
of CCl4?
1 mole CCl4
5.24 x 1025 molec. CCl4
6.02 x 1023 molec. CCl4
1
87.0
Moles CCl4
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C. Molar Mass
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1. Definition

• molar mass is the mass (in grams) of 1 mole of
  any element or compound
• units for molar mass g/molExample Hydrogens
  molar massis 1.008 g/mol

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• the molar mass of any element equals the average
  atomic mass on the periodic table in grams

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Use your periodic table

• 1 mol He 4.0026 grams He
• 1 mol Ca 40.08 grams Ca
• Other representation for Helium
• 1 mol He 4.0026 grams He
• 4.0026 grams 1 mol He

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(use a periodic table)

• the molar mass of iron is 55.85 g/mol
• 55.85 g 1 mole
• clean fraction 55.85g Fe
• 1 mol Fe

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• the molar mass of gold is 196.967g/mol
• 196.967g Au 1 mol Au
• clean fraction 196.967g Au
• 1 mol Au

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• anytime you want to convert from mass (grams) to
  moles or moles to mass (grams), use molar mass!
• Tip if you see mass (or grams) use your
  periodic table

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B. Calculating with Molar Mass
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B. Calculating with molar mass

• EX 1 Determine the mass of 3.50 mol of copper.

From the p.t ? Copper 63.546g Cu 1 mol Cu
g Cu
3.50 mol Cu
63.546g Cu
222
1 mol Cu
1
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Ex. 2 Determine the number of moles in 11.9 kg of
aluminum.
From the p.t ? Aluminum 26.982g Al 1 mol Al
11.9 kg Al
1000g Al
1 mol Al
441
mol Al
1 kg Al
26.982g Al
1
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Practice Box
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1. Determine the number of moles in 150 g of
sulfur
From the p.t ? Sulfur 32.066g S 1 mol S
150g S
1 mol S
4.68
mol S
1
32.066g S
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2. Determine the mass of 8.95 mol of Li
From the p.t ? Lithium 6.941g Li 1 mol Li
8.95 mol Li
6.941 g Li
62.1
g Li
1
1 mol Li
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3. Determine the mass, in kg, of 12.4 mol of Na.
From the p.t ? Sodium 22.990g Na 1 mol Na
0.285
kg Na
12.4 mol Na
22.990g Na
1 kg
1
1 mol Na
1000g
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C. Mixed Problems
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Tips for solving mole problems

• If you see atoms, molecules, or formula
  units mentioned in the problem, write
• 1 mole X 6.02 X 1023 atoms, molecules,
• formula units X .
• X element or compound

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Tips for solving mole problems

• 2. If you see mass involved in the problem, write
• 1 mol X (see periodic table) g X
• X element

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Mole Road Map
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Ex 1. Determine the mass of 4.56 x 1024 atoms of
silver.
end
Start
1
2
From the p.t ? Silver 107.868g Ag 1 mol Ag
1
2
4.56 x 1024 atoms Ag
107.868g Ag
1 mol Ag
6.02 x 1023 atoms Ag
1
1 mol Ag
817
g Ag
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Ex. 2 Determine the number of atoms in 100 g of
aluminum
Start
end
1
2
From the p.t ? aluminum 26.982g Al 1 mol Al
1
2
100 g Al
1 mol Al
6.02 x 1023 atoms Al
1 mol Al
26.982g Al
1
Atoms Al
2.23 x 1024
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Practice

• 1. Determine the number of atoms in 0.46 g of
  copper.
• 2. Determine the mass (in kg) of 5.98 x 1026
  atoms of potassium.
• 3. Which has more atoms, 26.982 g of aluminum or
  4.003 g of helium?

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1. Determine the number of atoms in 0.46 g of
copper.
Start
end
1
2
1
2
0.46g Cu
1 mol Cu
6.02 x 1023 atoms Cu
1 mol Cu
63.546 g Cu
1
Atoms Cu
4.36 x 1021
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2. Determine the mass (in kg) of 5.98 x 1026
atoms of K.
end
Start
1
2
1
2
5.98 x 1026 atoms K
39.098g K
1 mol K
1 kg K
6.02 x 1023 atoms K
1
1 mol K
1000g K
kg K
38.8
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3. Which has more atoms, 26.982 g of aluminum or
4.003 g of helium?
Start
end
1
2
26.982g Al
1 mol Al
6.02 x 1023 atoms Al
1 mol Al
26.982 g Al
1
Atoms Al
6.02 x 1023
4.003g He
1 mol He
6.02 x 1023 atoms He
1 mol He
4.003 g He
1
Atoms He
6.02 x 1023
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I dont get atoms
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A closer look

• If 4 grams of helium is equal to one mole of
  helium atoms
• and12 grams of carbon is equal to one mole of
  carbon atoms
• How can we explain1 mole 6.02 X x 1023 atoms?

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1 mole He 1 mole C 4.006
g/mol 12.001 g/mol6.02 X 1023 atoms He
6.02 X 1023 atoms C
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Conclusion

• Helium atoms are smaller than carbon atoms

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Dont forget what you learned before

• What does a mass number of 4 represent?
• Answer protons neutrons

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Mole and Weight Relationships of Water and its
Parts

• 2 moles 1 mole 1 mole
• H O H2O

                                 
2 1.01 g 16.00 g 18.02 g
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2 moles 1 mole 1 mole
H O H2O
2 1.01 g 16.00 g 18.02 g