Transcript The Mole - EARJ Chemistry

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The Mole & Stoichiometry
- the study of the
quantitative
aspects of
chemical
reactions.
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Atoms, molecules, ions, are too small to be
counted individually.
Atoms are extremely
small; most have
diameters between
1 x 10-10 m and
5 x 10-10 m
• 4 million atoms could line up and fit
across the head of a pin. To be able to
view atoms you must magnify them 30
million times, this is just enough to
make them visible.
In order to communicate, scientists needed a
counting unit for very small particles such as: atoms,
molecules,ions
The mole
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The Mole
• Similar to a dozen, except instead
of 12, it’s 602 billion trillion
602,000,000,000,000,000,000,000
• 1 mole =
6.02 X 1023
particles
• This number is named in honor of
Amedeo Avogadro _________
(1776 – 1856),
Counting Units
Object
Number
Unit
Eggs,bananas
12
dozen
sheets of paper
500
ream
shoes
2
pair
Atoms,molecules,
ions
?
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The Mole
• 1 dozen cookies = 12 cookies
• 1 mole of cookies = 6.02 X 1023 cookies
• 1 dozen cars = 12 cars
• 1 mole of cars = 6.02 X 1023 cars
• 1 dozen Al atoms = 12 Al atoms
• 1 mole of Al atoms = 6.02 X 1023 atoms
Note that the NUMBER is always the same,
but the MASS is very different!
Mole is abbreviated mol
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Mole and Mass Relationship
• Look what makes the mole such a great unit:
1 atom Carbon-----------------------------12 u
1 mole Carbon ---------------------------- 12g
1 atom Oxygen----------------------------- 16u
1 mole Oxygen ----------------------------- 16g
1 molecule of H2O -------------------- 18u
1 mol of H2O ------------------------ 18g
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Mole Map
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Mole Relationship
mol
________mass, g______ 6.02 x 1023
1mol Ca ________ 40g________6.02 x 1023 atoms
1mol CO2
______ 44g _______6.02 x 1023 molecules
Learning Check:
1. Number of atoms in 0.500 mole of Al
a) 500 Al atoms
b) 6.02 x 1023 Al atoms
c) 3.01 x 1023 Al atoms
2.Number of moles of S in 1.8 x 1024 S atoms
a) 1.0 mole S atoms
b) 3.0 mole S atoms
c) 1.1 x 1048 mole S atoms
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Calculations with Molar Mass
molar mass
Grams
Moles
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Converting Moles and Grams
Aluminum is often used for the structure
of light-weight bicycle frames. How
many grams of Al are in 3.00 moles of
Al?
Learning Check!
1. The artificial sweetener aspartame
(Nutra-Sweet) formula C14H18N2O5 is
used to sweeten diet foods, coffee
and soft drinks. How many moles of
aspartame are present in 225 g of
aspartame?
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Atoms/Molecules and Grams
How many atoms of Cu are
present in 35.4 g of Cu?
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Learning Check!
How many atoms of K are present in
78.4 g of K?
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Learning Check!
What is the mass (in grams) of 1.20 X
1024 molecules of glucose (C6H12O6)?
Moles and Reactions
• The coefficient of a balanced chemical
reaction represents the number of moles of
all substances involved.
CH4 + 2O2
Mole ratio:
1
:
2
=>
:
CO2 + 2 H2O
1
:
2
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Write the mole and mass ratio for the reaction of
decomposition of HI
Steps:
1.
Write and balance the chemical equation:
H2
+ I2
=> HI balancing
H2
+ I2
=> 2HI
2. Write the mole ratio:
1
:
1
: 2
3. Convert the mole ratio to mass ratio by multiplying the mole by the
molecular mass of the substance.
2g
:
253.8g : 255.8g
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Write the mole and mass ratio for
the combustion of C3H6
We saw that:
• The coefficients in a balanced chemical equation
shows how many moles of one reactant are needed
to react with other reactants and how many moles
of product will be formed.
• Stoichiometry is the method by which we can
relate substances in a chemical reaction.
Stoichiometry is basically the same as a recipe for
cooking .
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• 1. How many moles of C3H6 are required to
produce 260g of water?
C3 H6 + O2 => CO2 + 6H2 O
• 2. How much carbon dioxide will be formed
when 500g of oxygen burns?
Given the combustion of ethanol:
• 1. How much oxygen is required in order to
burn 700g of ethanol?
• 2. How much carbon dioxide is produced
when 6 moles of ethanol burns?
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