Avogadro’s
and the Mole
Moles
• a mole is the number of
carbon atoms in exactly 12g
of carbon.
• a mole is a unit of
measurement, just like
grams…
Grams  Moles
• the use of molar mass allows
the calculation of the mass of
a given number of moles (or
vice versa)
Example
• What is the mass of 3.25mol of CO2?
Example 2
• How many moles of N2 are there in 50.0g of
N2?
#mol =
g/mol
• remember the units of molar
mass are g/mol and can be
calculated using a given mass
divided by a given number of
moles
Example
• If 0.140mol of acetylene gas has a mass of
3.64g, what is the molar mass of acetylene?
g/mol =
Molecules  Moles
• Avogadro learned that there
23
are 6.02x10 molecules in
every mole! We can use that
now to convert molecules
first to moles and then
change it up!
Example
• How many moles are there in 6.489 x 1025
molecules of copper(II)sulfate?
Example 2
• How many molecules are contained in 45.8
grams of NaOH?