Atoms are really, really small…… We can not work with individual atoms or AMU’s in the lab....
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Transcript of Atoms are really, really small…… We can not work with individual atoms or AMU’s in the lab....
![Page 1: Atoms are really, really small…… We can not work with individual atoms or AMU’s in the lab. Atomic Mass Unit WHY? Because we can’t see things that small!](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649ebb5503460f94bc2c76/html5/thumbnails/1.jpg)
The MoleUnit 7: Stoichiometry – Part I
Mrs. Callender
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Lesson Essential Questions
What is a mole?
What is a mole used for?
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Atoms are really, really small……
We can not work with individual atoms or AMU’s in the lab. Atomic Mass
Unit WHY?Because we can’t see
things that small!
![Page 4: Atoms are really, really small…… We can not work with individual atoms or AMU’s in the lab. Atomic Mass Unit WHY? Because we can’t see things that small!](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649ebb5503460f94bc2c76/html5/thumbnails/4.jpg)
We as scientists work with portions of matter large enough for us to SEE and MASS on a balance using units of……GRAMS
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This presents a problem…..
Click icon to add picture
A pile of atoms large enough for us to see
contains billions of
atoms.
Copper (II) Sulfate
So how would we keep track of that many atoms?
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Chemists came up with a new unit.
The
MOLE
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Equivalents or Conversion Factors
1 dozen eggs = 12 eggs
1 rooster = two legs
1 ream of paper = 500 pieces of paper
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Equivalents or Conversion Factors
1 mole = 6.02 x 1023
There are EXACTLY 12 grams of Carbon-12 in 1 mole of Carbon-12.
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Avogadro’s Number
6.02 x 1023
He studied gases and discovered that no
matter what the gas, there were the same number of molecules
present.Named in honor of Amadeo Avogadro.
1776 - 1856
I did not discover the
number. It was just named after
me.
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Units for Avogadro’s Number
1 mole = 6.02 x 1023 (many different units)
For instance:
1 mole of pennies = 6.02 x 1023
pennies.This amount is equivalent to 7 stacks of pennies from the Earth to the moon.
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Units for Avogadro’s Number
1 mole Mg= 6.02 x 1023 atoms.
1 mole NaCl= 6.02 x 1023
molecules.1 mole Cl2 = 6.02 x 1023
molecules.1 mole SO4
-2 = 6.02 x 1023 ions.
R
em
em
ber:
HO
FB
rINC
l
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Calculating Formula Mass
Calculate the formula mass of NaCl.
6
Na22.98
97
17
Cl35.45
3
22.99 g + 35.45 g = 58.44 g Therefore, 1 mole of NaCl (6.02
x 1023 molecules) has a mass of 58.44 g
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Calculating Formula Mass
Calculate the formula mass of K2O.
19
K39.09
83
6
O15.99
94
2(39.10) g + 16.00 g = 94.2 g Therefore, 1 mole of K2O (6.02 x
1023 molecules) has a mass of 94.2 g
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Calculating Formula Mass
Calculate the formula mass of (NH4)2SO4.
7
N14.00
67
6
O15.99
942(14.01) g + 8(1.01) g + (32.01) + 4(16.00) g = 132.11 g
Therefore, 1 mole of (NH4)2SO4 (6.02 x 1023 molecules) has a mass of 132.11 g
1
H1.007
94
16
S32.06
6
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Calculating Formula MassCalculate the formula mass of
CuSO4
5 H2O.29
Cu63.54
6
6
O15.99
9463.55 g + 32.01g + 4(16.00) g + 5[2(1.01)+16.00] = 249.56 g
1
H1.007
94
16
S32.06
6
.
Therefore, 1 mole of CuSO4 5 H2O (6.02 x 1023 molecules)
has a mass of 249.56 g
.
This type of formula is called a hydrate. It is a salt with water physically attached to it.Example: A salt container with rice intermixed.
Since the water is physically attached how could it be removed?
By heating. When the water is removed the remaining salt is called anhydrous.