What is a Mole
 How many socks come in a pair?
 2
 How many eggs are in a dozen?
 12
 How many eggs come in a gross?
 144
 How many pencils come in a ream?
 500
So how many things come in a
mole?
Conversion Review
 Dimensional Analysis
Example Problems
Relative Mass
Molar Mass
Using molar mass
Converting between mass and
atoms
Chemical Formulas and the Mole
Molar Mass of a Compound
 Determine the molar mass of each of the following
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compounds:
NaOH
CaCl2
KC2H3O2
C2H5OH
HCN
CCl4
(NH4)3PO4
Converting moles to mass
 The characteristic odor of garlic is due to the
compound (C3H5)2S. What is the mass of 2.5 moles of
(C3H5)2S?
 What is the mass of 3.25 mol of H2SO4?
Converting Mass to Moles
 Calculate the number of moles in 325 g of Calcium
hydroxide Ca(OH)2?
 Calculate the number of moles in 22.6 g of AgNO3.
Mass to Number of Particles
 How many Aluminum Chloride molecules are present
in 35.6 g of AlCl3
 How many Al atoms are there?
 How many Cl atoms are there?
Example
 Aluminum oxide (Al2O3) when dissolved in water
breaks apart into ions (Al3+ and O2-) how many moles
of Al3+ will be produced when 1.5 moles of Al2O3 are
dissolved in water?
Examples
What is the molar mass of ethanol C2H5OH?
1.
 How many ethanol molecules are present in 45.6 g?
 How many carbon atoms are there in 45.6 g of ethanol?
 How many hydrogen atoms are there in 45.6 g of ethanol?

How many oxygen atoms are there in 45.6 g of ethanol?
A sample of sodium sulfite Na2SO3 has a mass of 2.25 g
2.
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
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How many molecules of sodium sulfite are there?
How many atoms of sodium are there?
How many atoms of Sulfur are there?
How many atoms of oxygen are there?
Percent Composition
 The molar mass of NaOH is
 Na – 22.98 g/mol
 O – 16 g/mol
 H – 1 g/mol
 Total: 39.98 g/mol
Example
 NaHCO3
Empirical Formula
Example
 Find the empirical formula for hydrogen peroxide
which has a molar mass of 34 g/mol and is 5.9%
Hydrogen and 94.1% Oxygen
Molecular Formula
Example
Example
 Find the empirical and molecular formula for a
compound that is 26.5% K, 35.4% Cr, and 38.1% O and
has a molar mass of 294.2 g/mol.
Example
 Find the empirical and molecular formula for a
compound that is 26.7% carbon, 2.2% hydrogen, and
71.1% oxygen and has a molar mass of 90 g/mol.