Transcript The Mole - Rothschild Science

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Conserving Matter
Read Conserving Matter: p.153
Do the Reading Guide- tape it into your CB when it
is complete!
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Warm UpMake sure your reading guide is complete and
taped in you CB.
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C.2 Accounting for Atoms
The law of conservation of matter says that
“matter is neither created nor destroyed”.
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Chemical Equations
In a chemical reaction, the number of atoms
of each element needs to be the same on
both sides of the arrow.
Reactants
CH4 + O2 
Products
CO2 + H2O
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Balancing an Equation
CH4 + O2 
CO2 + H2O
a. Count the atoms on each side of the equation.
b. Place coefficients in front to make the sides equal.
c. Recheck to make sure it worked
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Try these!
a.
NH3 
H2 + N2
b. CaCO3 
c.
HCl +
CaO +
Ca(OH)2 
CO2
CaCl2 + H2O
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How do I read a chemical equation?
CaCO3  CaO + CO2
One formula unit of calcium carbonate reacts to form one
formula unit of calcium oxide and one molecule of
carbon dioxide.
One mole of calcium carbonate reacts to form one mole of
calcium oxide and one mole of carbon dioxide.
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Work on the balancing equations WS
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The Mole
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6.02 X 10
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Read C.5, p.161
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The mole is a unit of measure
Developed
because it is
impossible to
work with
individual atoms
or molecules.
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The Mole
• A counting unit
• Similar to a dozen (except instead of
12, it’s 602 billion trillion
602,000,000,000,000,000,000,000)
• 6.02 X 1023 particles/mole
(in scientific notation)
• This number is named in honor of
Amedeo _____________ (1776 – 1856),
who studied quantities of gases and
discovered that no matter what the gas
was, there were the same number of
molecules present
Just How Big is a Mole?
• Enough soft drink cans to cover the surface
of the earth to a depth of over 200 miles.
• If you had Avogadro's number of unpopped
popcorn kernels, and spread them across
the United States of America, the country
would be covered in popcorn to a depth of
over 9 miles.
• If we were able to count atoms at the rate of
10 million per second, it would take about 2
billion years to count the atoms in one mole.
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Where Did it Come From?
• It was NOT just picked!
It was MEASURED.
• One of the better
methods of measuring
this number was the
Millikan Oil Drop
Experiment
• Since then we have
found even better ways
of measuring using
x-ray technology
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You must know…
A mole of anything = 6.02 x 1023 particles
Look! I have a bunch of samples for you to look at!
It took me all break to count all these particles!
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Look at the periodic table!
The atomic mass of each element is
written below the element
symbol.
The units on atomic mass are
grams per mole (g/mol)
So we have a bunch of conversion
factors for doing cool
calculations!
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Conversion Flow Chart
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Convert
1. Convert 6.17g of carbon to moles
2. Convert 2.3g Na to moles
3. Convert 0.05 moles of Cl to grams.
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Warm Up
Convert the following:
a. 3.4 g of nitrogen to moles
b. 0.72mol of fluorine to grams
c. 10.9 g of magnesium to moles.
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Molar Mass
The molar mass of a compound is the sum of
the atomic masses of all the atoms in the
compound.
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Find the Molar Mass of
Calcium Chloride
CaCl2
The process
1. List how many atoms of each element?
2. Determine the atomic mass of each element.
3. Multiply by the number of atoms
4. Add them up!
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You learned to do this last semester!
Calculate the molar mass of carbon dioxide?
CO2
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Now try dinitrogen tetroxide
N2O4
Remember the process
1. How many atoms of each element?
2. What is the atomic mass of each element.
3. Multiply by the number of atoms
4. Add them up!
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How did you do?
N2 O 4
2 Nitrogen x 14.01 = 28.02 g/mol
4 Oxygen x 16.0 = 64.00 g/mol
• 1 mole of N2O4
= 92.02 g/mol
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More Practice!
Do C.6 in your CB
p. 163
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Convert the following
1. 6.2g of NaCl to moles
2. 3.6 g of water to moles
3. 1.20mol to water to grams
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Moles and Mass WS
Work on the WS…
Change the #5 to just say CuSO4
(Cross out the 5H2O)
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Conversions using Avagadros Number
How many atoms in 1.2 moles of Cu?
How many atoms in 0.5 moles of Carbon?
How many atoms in 1.3 mol of Li?
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Going backwards
How many moles in 3.2 x 1023 atoms of C?
How many moles in 5.6 x 1022 atoms of F?
How many moles in 5.6 x 1022 molecules of
water?
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The Mole and Avagadros number
WS
Work on the WS…
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Going all the way!
How many atoms in 0.30g of Lithium?
How many molecules in 3.7g of water?
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How many grams in 4.31 x 1023 atoms of Cu?