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The Mole

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Title: The Mole


1
The Mole
Chapter11
2
I. Atoms, Molecules, and Formula units
3
I. Atoms, Molecules, and Formula units
  • The terms atom, molecule, and formula units can
    be used to represent very similar things.

4
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
5
Metals Non-Metals
Non-Metals
Metals!
6
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
7
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
8
  • 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?

9
  • Remember, a compound, molecular or ionic, is made
    up of at least 2 atoms from the periodic table.

10
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
11
I. The mole and Avogadros number
12
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.

13
An animal
14
(No Transcript)
15
A birth mark
16
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)

17
  • Example 1 atom of hydrogen 1.008 amu of
    hydrogen

18
  • 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)

19
  • Example 1 mole of hydrogen 1.008 grams of
    hydrogen

20
  • 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.

21
Its really just a word to represent a number
22
Just like
  • a couple of cookies __2__ cookies
  • a dozen doughnuts _12_ doughnuts
  • a gross of geese __144___ geese

23
  • 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

24
  • "mole" represents the number 6.0221367 x 1023 or
    602000000000000000000000

25
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

26
  • 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.

27
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.

28
In your box
  • 1 mole
  • 6.02 X 1023 atoms, molecules, or formula units

29
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

30
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

31
Mole day is generally celebrated on October 23
1023 AT 602AMget it?
32
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

33
Why use such a big number?
  • We use moles when it comes to atoms and
    molecules
  • take a guess?

Because atoms are so small
34
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.

35
The two conversion factors
1 mol___ 6.02 x 1023
6.02 x 1023 1 mole
and
atoms, molecules, or formula units
36
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
37
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
38
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
39
Practice Box
40
Practice
  • 1.
  • 2.
  • 3.

3.37 x 1022
Atoms Pu
19.9
Moles of Phosphorus
87.0
Moles CCl4
41
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
42
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
43
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
44
C. Molar Mass
45
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

46
  • the molar mass of any element equals the average
    atomic mass on the periodic table in grams

47
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

48
(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

49
  • the molar mass of gold is 196.967g/mol
  • 196.967g Au 1 mol Au
  • clean fraction 196.967g Au
  • 1 mol Au

50
  • 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

51
B. Calculating with Molar Mass
52
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
53
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
54
Practice Box
55
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
56
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
57
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
58
C. Mixed Problems
59
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

60
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

61
Mole Road Map
62
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
63
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
64
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?

65
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
66
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
67
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
68
I dont get atoms
69
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?

70
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
71
Conclusion
  • Helium atoms are smaller than carbon atoms

72
Dont forget what you learned before
  • What does a mass number of 4 represent?
  • Answer protons neutrons

73
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
74
2 moles 1 mole 1 mole
H O H2O
2 1.01 g 16.00 g 18.02 g
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