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Write a net ionic equation for the following:
◦ Aqueous solutions of calcium chloride and sodium
carbonate form the precipitate calcium carbonate
◦ HI (aq) + Na2S (aq)  H2S (g) + NaI (aq)
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How many donuts are in 6.7 dozen donuts?
Use dimensional analysis.
If one ream of paper is 500 sheets, how
many sheets are in 3.4 reams of paper?
Daily science Jan 14
The Mole
Pg. 71
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A way to group atoms together
12 is to a dozen as 6.02 x 1023 is to a
mole
Avogadro’s number = 6.0221367 x 1023
Based off of number of carbon atoms in
12 g of carbon -12
602000000000000000000000 atoms in
one mole
Can be used to count: molecules, atoms,
particles
Definition of a Mole
Can write a conversion factor using
Avogadro’s number to convert from moles
to particles or particles to moles
 Moles to particles: x 6.02 x 1023
1 mol
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Particles to moles: x 1 mol
6.02 x 1023
Converting moles
Determine the number of atoms in 2.50
moles of Zn
 Calculate the number of molecules of H2O
in 11.5 moles.
 How many moles is 5.75 x 1024 atoms of
Al?
 How many moles is in 3.58 x 1023 units of
ZnCl2
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Examples
Moles of different substances have
different masses
 Called molar mass (mass in grams of one
mole of a substance)
 Units: g/mol
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Mass and the Mole
What is the molar mass of Silicon?
 What is the molar mass of Cl2?
 What is the molar mass of H2O
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Examples
To find the mass of a certain amount of a
substance, use a conversion factor for
molar mass
 Mass to moles: x 1 mole
molar mass
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Moles to mass: x molar mass
1 mole
Conversions using molar mass
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How many moles are in the following:
◦ 25.5 g of Ag
◦ 300.0 g S
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What is the mass of the following amount
of moles:
◦ 3.45 mol of Co
◦ 42.6 mol Si
Examples
Multi step problem
 Combine both conversion factors
 Mass to atoms: x1 mol
x 6.02 x 1023 atom
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molar mass
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Atoms to mass: x 1 mol x
6.02 x 1023
1 mol
molar mass
1 mol
Conversions from mass to atoms
and atoms to mass
Convert 3.40 x 1022 atoms of He into
grams
 Convert 1.00 x 1024 molecules of MgO into
grams
 Convert 55.2 g Li into atoms
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Examples